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Keto Blooming Onion Recipe (Easy and Crispy) 🧅

Cast Iron Keto
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Updated:
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4.72 from 14 votes

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This recipe for a Keto Blooming Onion is easy, delicious, and makes a great appetizer! Complete with a recipe for Horseradish dipping sauce. This ketofied version of the classic appetizer is a far cry nutritionally from their restaurant counterparts, but right on par in the flavor department.

Overhead shot; keto blooming onion on parchment with dipping sauce in the foreground.
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Preparation and cooking overview

Preparing keto-blooming onion takes only 40 minutes. Cut the onions into petals, dip in beaten egg, coat with flour mixture, and drizzle with olive oil. Then, bake in the oven at 400°F (200°C) for 30 minutes until golden.

Chef's note

Get creative with your seasoning by adding a pinch of your favorite herbs or spices to the flour mixture – think garlic powder, fresh herbs, or even a touch of grated Parmesan for an extra layer of flavor. If you're looking to up the heat, amp up the cayenne pepper for a spicier kick.

  • Prep Time: 10 minutes
  • Cooking Time: 30 minutes
  • Total Time: 40 Minutes
  • Difficulty Level: Easy
  • Recipe Makes 6 Servings

For more inspiration check out our Snacks recipe.

🧅 Ingredients for this keto blooming onion recipe

  • 3 medium onions
  • 2 large eggs
  • ½ cup almond flour
  • ¼ cup coconut flour
  • 1 tablespoon paprika
  • ½ teaspoon salt
  • ¼ teaspoon cayenne pepper
  • 1 tablespoon olive oil

Horseradish sauce

  • ¼ cup mayonnaise
  • 1 tablespoon ketchup
  • 1 ½ tablespoons prepared horseradish
  • ¾ teaspoon cayenne pepper
  • ½ teaspoon paprika
  • Sea salt and freshly ground pepper to taste

Ingredient substitutions

Don't fret if there's a particular ingredient you don't have. These handy substitutions are here to save the day:

  • Cayenne pepper: Use red pepper flakes as a substitute for cayenne pepper in this recipe.
  • Paprika: If you have chili powder, use it instead of paprika. Chili powder is typically a blend of different spices, including paprika, so it can add a similar touch of spiciness to the dish.

Additional ingredients

Want to take this appetizer to a whole new level of deliciousness? Add these flavorful ingredients:

  • Crushed pork rinds: Mix crushed pork rinds with flour before coating the onion petals. They will provide a crispy and savory texture to the onion.
  • Garlic powder: Adding a dash of garlic powder to the coating mixture will enhance the savory flavors of the onion and provide a delicious aroma.
  • Fresh herbs: Use chopped fresh herbs such as parsley, chives, or basil as a garnish to add freshness and a pop of color to the final dish.
  • Lemon zest: Grating some lemon zest over the finished blooming onion will add a touch of brightness and citrusy notes, balancing the flavors.

Cooking tools required

To make this keto-blooming onion recipe, you will need the following tools:

  • 10.5" cast-iron skillet
  • 3 small bowls
  • Knife
  • Cutting board
  • Spoon
  • Measuring cups and spoons
  • Whisk
  • Aluminum foil

Tools substitute options

  • Cast-iron skillet: If you don't have a cast iron skillet, use a large oven-safe skillet or a baking dish for baking the onions.
  • Whisk: If you don't have a whisk, use a fork to beat the eggs.
  • Foil: If you don't have aluminum foil, use parchment paper or a lid to cover the skillet while baking.

How to make a gluten-free Baked Blooming Onion: step-by-step guide

Cooking methods

  • Baking

Preparation steps

  1. Gather and measure all the required ingredients.
  2. Peel the onions.
  3. Crack the eggs into a small bowl.

Cooking instructions

  1. Preheat oven to 400°F (200°C). Whisk the eggs in a small bowl. In another small bowl, mix together the almond flour, coconut flour, paprika, salt, and cayenne. In another small bowl, combine all of the ingredients for the sauce and refrigerate until ready to use.
  2. To cut the onions, start by cutting off ½ inch of the pointy side of the onion, then peel off the outside layer. Lay the onion cut side down. Then, starting a ½ inch from the top (the end that’s not cut off), make 4 cuts through the onion across from each other. Repeat between the cuts until you have between 8-12 cuts, depending on the size of your onion. Flip the onion over and gently fluff out the petals.
  3. Dip each onion into the egg mixture, making sure to coat the inside and outside of each petal, let the excess fall off, then dredge through the flour mixture. You can use a spoon to make sure you get flour on each petal. Place the onions in a large 10.5″ cast iron skillet and drizzle or spray with about 1 tablespoon of olive oil.
  4. Cover the skillet with aluminum foil and transfer to the oven. Bake covered for 15 minutes. Remove the foil and bake for another 15 minutes. If the onions haven’t browned enough, you may place them under your broiler set to high for 5 minutes until golden brown. Serve with the horseradish sauce.

Make the horseradish sauce

  1. Take an 8 to 10" horseradish root, peel it, and chop it into pieces.
  2. Add the chopped pieces to a small food processor. Add a little water, vinegar, and a pinch of salt, and blend. Transfer the prepared horseradish to an airtight jar.
  3. In a small bowl, add 1½ tablespoons of the prepared horseradish and combine it with other sauce ingredients, including mayonnaise, ketchup, cayenne pepper, and paprika.
  4. Your keto horseradish sauce is ready.

Chef's pro tip

Choose an onion of about softball size. For a uniformly coated and crispy onion, give each petal a luxurious dip into the egg mixture and let the excess drip off before dredging it through the flour mixture. Additionally, use a spoon to sprinkle flour on each petal for full coverage. This technique prevents clumping and ensures a beautiful, golden crust on every petal.

Close up of a single baked onion petal dipped into the horseradish dipping sauce

What to serve with a keto-blooming onion?

The blooming onion is a versatile keto appetizer that effortlessly complements a wide range of foods. The following dishes pair well with this recipe:

  • Sirloin Steak: The crispy texture and flavorful onion petals perfectly complement the tender and juicy steak.
  • Baked Chicken: Enjoy finger-licking goodness by serving baked chicken with the blooming onion.
  • Fried Zucchini: Serve fried zucchini alongside the blooming onion for a low-carb treat that perfectly complements the flavors and textures of the appetizer.
  • Crispy Bacon Strips: Serve crispy bacon strips alongside the onion for a delicious combination of savory flavors and contrasting textures.
  • Grilled Shrimp Bruschetta: It makes a delightful seafood pairing with the blooming onion, bringing a taste of coastal indulgence to your plate.
  • Pulled Pork Sliders: Enjoy tender and flavorful pulled pork sliders alongside the blooming onions for a satisfying and meaty combination that is sure to please.

How to make it healthier

  • Choose organic onions, eggs, and spices whenever possible.
  • To lower the sodium content, reduce the amount of salt or go for a low-sodium alternative. You can also enhance the flavor with herbs and spices instead.
  • Incorporate more nutrients by adding grated Parmesan cheese, ground flaxseed, or chia seeds to the coating mixture. These ingredients boost the fiber and healthy fat content of the recipe.

Time-saving tips

  • Use an apple cutter: Peel and trim a medium-sized onion, then cut about ½ inch off the top. Position an apple cutter over the onion's flat top, press down to create evenly spaced cuts, and gently separate the petals.

What can I prepare ahead of time?

  • Mix the dry ingredients: Combine the almond flour, coconut flour, paprika, salt, and cayenne pepper in a bowl and store it in a sealed container. Having the dry mixture ready will save time and make the coating process smoother.
  • Make the horseradish sauce: Prepare the horseradish sauce and store it in the refrigerator until it is ready to serve. Horseradish sauce can be stored in an airtight jar in a fridge for up to 2 weeks.

Storage and reheating instructions

Storage tips

  • Refrigerator: For storage, tightly wrap the leftover keto-blooming onion with plastic wrap or place it in an airtight container. Refrigerate within 2 hours and consume within 2-3 days for optimal taste.

Note: Freezing is not recommended for the keto-blooming onion, as the texture may become soggy upon thawing.

Reheating best practices

  • Microwave: Place a single portion of the keto-blooming onion on a microwave-safe plate and reheat for 1-2 minutes on high power until heated.
  • Oven: Preheat the oven to 350°F (175°C) and place the onion on a baking sheet. Heat for 10-15 minutes until warm and crispy.
  • Air fryer: Place the leftover onion in the air fryer basket and heat it at around 350°F (175°C) for 5-7 minutes or until it reaches your desired level of warmth and crispiness. Keep an eye on it to avoid overcooking.

Recipe wrap-up and conclusion

And there you have it, a crispy, golden Keto Blooming Onion that's as delightful to look at as it is to savor. With each petal offering a burst of flavors and textures, this low-carb treat is perfect for sharing with friends at gatherings, as an appetizer to impress, or simply as a snack during your cozy movie nights.

With its enticing aroma and indulgent taste, this dish is ready to steal the show at any mealtime – be it lunch, dinner, or a satisfying snack. Don't just wait for special occasions; make any day extraordinary with this mouthwatering recipe.

Frequently asked questions

Yes, onions are keto-friendly. While onions do contain carbohydrates, they are relatively low in net carbs, making them suitable for a keto lifestyle when consumed in moderation. Onions also provide fiber and various essential nutrients, making them a flavorful and nutritious addition to keto recipes.

Absolutely! The keto-blooming onion can be made in an air fryer for healthier cooking. Simply follow the recipe instructions for coating the onion petals and place them in the air fryer. Cook at 400°F (200°C) for about 15 minutes, flipping halfway through, until they turn golden brown and crispy. In just a few minutes, you'll have a fantastic air-fried blooming onion ready to enjoy.

No, this is the best ratio of flour mixture that we have found. It creates the perfect crust. Just almond flour tends to burn, and just coconut flour tends to, well, be too coconutty.

You can serve these as an appetizer, side dish, or snack! They're great with steak. We highly recommend the horseradish sauce that is given with this recipe.

The exact carb count may vary depending on the size of the onion used and the specific measurements of the ingredients. However, as a general guideline, a standard serving size of a keto-blooming onion typically contains around 9 to 10 grams of net carbs.

You can use any size of onion for this recipe. You can also use mini blooming onions for individual servings. Choose smaller onions and follow the same cutting and coating process described in the recipe. Adjust the baking time accordingly, reducing it slightly since smaller onions will cook faster.

  • To cut the onions, start by placing them on a cutting board and slicing off a ½ inch of the pointy side of the onion then peel off the outside layer.
  • Lay the onion cut side down.
  • Then, starting a ½ inch from the top (the end that's not cut off), make 4 cuts through the onion across from each other.
  • Repeat between the cuts until you have between 8-12 cuts depending on the size of your onion.
  • Flip the onion over and gently fluff out the onion petals.

📖 Recipe

Overhead shot; keto blooming onion on parchment with dipping sauce in the foreground.

Keto Blooming Onion

This recipe for Keto Blooming Onions is easy, delicious, and makes a great appetizer! Complete with a recipe for Horseradish dipping sauce.
4.72 from 14 votes
Print Rate Pin Recipe
Course: Appetizer, Side Dish
Cuisine: American
Keyword: comfort, easy, gameday
Prep Time: 10 minutes
Cook Time: 30 minutes
Total Time: 40 minutes
Servings: 6
Calories: 141kcal

Ingredients

  • 3 medium onions
  • 2 large eggs
  • ½ cup almond flour
  • ¼ cup coconut flour
  • 1 tablespoon paprika
  • ½ teaspoon salt
  • ¼ teaspoon cayenne pepper
  • 1 tablespoon olive oil

Horseradish Sauce:

  • ¼ cup mayonnaise
  • 1 tablespoon ketchup
  • 1 ½ tablespoons prepared horseradish
  • ¾ teaspoon cayenne pepper
  • ½ teaspoon paprika
  • Salt and pepper to taste
US Customary - Metric

Instructions

  • Preheat oven to 400° F. Whisk the eggs in a small bowl, in another small bowl mix together the almond flour, coconut flour, paprika, salt, and cayenne. In another small bowl combine all of the ingredients for the sauce, refrigerate until ready to use.
  • To cut the onions, start by cutting off a ½ inch of the pointy side of the onion then peel off the outside layer. Lay the onion cut side down. Then, starting a ½ inch from the top (the end that’s not cut off), make 4 cuts through the onion across from each other. Repeat between the cuts until you have between 8-12 cuts depending on the size of your onion. Flip the onion over and gently fluff out the petals.
  • Dip each onion into the egg mixture making sure to coat the inside and outside of each petal, let the excess fall off then dredge through the flour mixture, you can use a spoon to make sure you get flour on each petal. Place the onions in a large 10.5″ cast iron skillet and drizzle or spray with about 1 tablespoon of olive oil.
  • Cover the skillet with aluminum foil and transfer to the oven. Bake covered for 15 minutes, remove foil and bake another 15 minutes. If the onions haven’t browned enough you may place them under your broiler set to high for 5 minutes until golden brown. Serve with the horseradish sauce.

Make the horseradish sauce

  • Take an 8 to 10" horseradish root, peel it, and chop it into pieces.
  • Add the chopped pieces to a small food processor. Add a little water, vinegar, and a pinch of salt, and blend. Transfer the prepared horseradish to an airtight jar.
  • In a small bowl, add 1½ tablespoons of the prepared horseradish and combine it with other sauce ingredients, including mayonnaise, ketchup, cayenne pepper, paprika, and seasonings.
  • Your keto horseradish sauce is ready.

Notes

Nutritional info does not include sauce.

Nutrition

Nutrition Facts
Keto Blooming Onion
Amount Per Serving
Calories 141 Calories from Fat 81
% Daily Value*
Fat 9g14%
Saturated Fat 2g13%
Cholesterol 55mg18%
Sodium 228mg10%
Potassium 127mg4%
Carbohydrates 9g3%
Fiber 4g17%
Sugar 2g2%
Protein 5g10%
Vitamin A 689IU14%
Vitamin C 4mg5%
Calcium 43mg4%
Iron 1mg6%
*

Nutritional values are estimates only and do not include carbs from sugar alcohols.

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Reader Interactions

Comments

  1. Marsha Whitt says

    Would this bake up well if I completely cut the onion into petals and prepared the petals accordingly then baked in one layer? Would like to serve the petals at a tea party.

    Reply

    • Cast Iron Keto says

      They should work perfectly that way!

      Reply

  2. Harris Sweet says

    Can I use just coconut flakes instead of almunds?

    Reply

    • Cast Iron Keto says

      Hi Harris - well, I mean I guess you could make a coconut style blooming onion. We haven't tried it so we can't say that it will work but you could try using our breading that we use in our Keto Coconut Shrimp recipe as the breading for the onion. Let us know if you give it a go.

      Reply

  3. Darren Lovely says

    4 stars
    Turned out pretty good, in the future I would use a jumbo white onion, I just used a regular yellow onion as that is all I had, did not make the dip as had something close enough in the fridge

    Reply

  4. Jamie Hunt says

    Can you use just almond flour?

    Reply

  5. Ginger Wroot says

    Looks so yum! How many servings did you calculate for this recipe? --Ginger

    Reply

    • Alex Lester says

      Hi Ginger, the serving size can always be found at the top of the recipe card. it's super small font so it's easy to miss. This recipe, with the 3 onions, serves 6. So, it's 1/2 an onion per serving. Hope this helps!

      Reply
4.72 from 14 votes (13 ratings without comment)

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