Air Fryer Blooming Onion with Horseradish Sauce
A showstopping appetizer featuring whole sweet onions hand-cut into delicate petals, double-breaded with a seasoned flour mixture, and air-fried until golden and crispy. The contrast of tender onion layers against the crunchy exterior is balanced by a tangy horseradish-spiked dipping sauce. Perfect for entertaining or special occasions when you want an impressive vegetarian centerpiece that looks restaurant-quality but comes together in under 45 minutes. This air fryer version delivers the same crispy satisfaction as the deep-fried classic with far less oil and mess.
Ingredients
- 2 large sweet onions, peeled
- 1 ½ cups all-purpose flourgluten-free 1-to-1 flour1:1dietarygluten-free
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- ¼ cup cornstarch
- 2 teaspoons garlic powder
- 2 teaspoons onion powder
- 3 teaspoons paprika powder
- ½ teaspoons salt, for breading
- ½ teaspoons black pepper
- ½ teaspoons cayenne pepper powder
- ½ cup buttermilk
- 2 large eggsaquafaba or flax egg3 tbsp aquafaba or 2 tbsp ground flax+6 tbsp watervegan
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Full guide → - ⅓ cup sour cream, for sauce
- 2 teaspoons horseradish, prepared
- ¼ cup ketchup
- ⅓ cup mayonnaise
- ¼ teaspoons salt, for sauce
- ¼ teaspoons paprika powder, for sauce
- ½ teaspoons dried oregano
- non-stick cooking spray
- fresh parsley, minced, optional(optional)
Instructions
- 1
Peel onions and slice off tops, leaving roots intact.
- 2
Turn onions upside down on cutting board.
- 3
Starting from outside of root, cut through to create slit, then rotate and make parallel cuts on opposite side, continuing around to create 18-20 evenly spaced cuts without severing petals.
- 4
Flip onions over and gently separate petals, cutting any remaining connected pieces.
- 5
Whisk together flour, cornstarch, garlic powder, onion powder, paprika, salt, pepper and cayenne in large bowl.
- 6
Dredge each onion in flour mixture, coating all petals thoroughly.
- 7
Whisk buttermilk and eggs together in separate bowl.
- 8
Dip flour-coated onions into egg mixture until fully coated.
- 9
Dredge in flour mixture again and place on cooling rack over baking pan for 10 minutes to set breading.
- 10
Preheat air fryer to 380F for 5 minutes.
- 11
Spray air fryer basket with non-stick spray and place onion petals facing up.
- 12
Spray top of onion generously.
- 13
Air fry at 380F for 12 minutes, then check color and cook 5 more minutes if needed for desired darkness.
- 14
Repeat with remaining onion.
- 15
For sauce, whisk together sour cream, horseradish, ketchup, mayonnaise, salt, paprika and oregano.
- 16
Serve onions immediately with chilled sauce and fresh parsley if desired.
Tips
Chill the dipping sauce for at least 30 minutes before serving; cold sauce contrasts beautifully with the hot crispy onion and helps cut the richness.
Let the breaded onions rest on the cooling rack for the full 10 minutes so the coating adheres properly and doesn't flake off during air frying.
For extra crispy petals, spray the onion again halfway through cooking and use the optional 5-minute extension.
Good to Know
Store leftover onion in airtight container in refrigerator for up to 2 days. Reheat in air fryer at 350F for 4-5 minutes to restore crispness. Sauce keeps refrigerated for 5 days.
Prepare and bread onions up to 4 hours ahead; refrigerate on cooling rack. Make sauce up to 1 day in advance. Air fry just before serving for best texture.
Serve immediately while petals are still crispy, with chilled sauce and fresh parsley. Pairs well with other appetizers, as a vegetarian centerpiece, or alongside grilled meats.
Common Mistakes
Cut too deeply between petals to avoid onion falling apart during cooking
Skip the 10-minute resting period to avoid breading flaking off in air fryer
Forget to spray onion generously to avoid uneven browning and dry patches
Use room-temperature sauce to avoid steam making onion soggy
Substitutions
Vegan Options
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Full guide →Gluten-Free Swaps
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General Alternatives
FAQ
Can I make this with red onions instead of sweet onions?
Yes, red onions work well and have a slightly sharper flavor. They may need an extra 2-3 minutes of cooking time to become tender due to their denser structure. Sweet onions remain the best choice for mildness and natural sweetness.
What if my onion breaks apart while cutting or cooking?
Take time with cuts and don't push petals apart too aggressively initially. If pieces separate during cooking, gather them on a separate rack and cook together, or chop remaining onion pieces and make crispy onion strings instead.
How long can I keep a cooked blooming onion and can I reheat it?
Cooked onions last 2 days refrigerated in an airtight container. Reheat in air fryer at 350F for 4-5 minutes to restore crispness. Cold onion becomes soggy and unappetizing, so reheating is essential for texture.