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Easy Oven Baked Blooming Onion Recipe | Crispy Baked Onion Appetizer

This easy oven-baked blooming onion delivers crispy, golden petals with bold seasoning and a tender center—no deep fryer needed. Serve hot with a zesty horseradish dipping sauce for a crowd-pleasing appetizer.
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Prep Time 25 minutes
Cook Time 30 minutes
Total Time 55 minutes
Servings 4 people

Ingredients
  

Ingredients

  • 1 large sweet onion (Vidalia or Walla Walla; 16–20 oz)
  • 2 large eggs
  • 3/4 cup buttermilk (or milk plus 1 tsp lemon juice)
  • 1 cup all-purpose flour
  • 3/4 cup panko breadcrumbs
  • 1 1/2 tsp kosher salt
  • 1 tsp smoked paprika
  • 1 tsp garlic powder
  • 1/2 tsp onion powder
  • 1/2 tsp ground black pepper
  • 1/4 tsp cayenne pepper (optional)
  • 2–3 tbsp neutral oil (avocado or canola), for drizzling
  • Cooking spray
  • 1/2 cup mayonnaise
  • 2 tbsp ketchup
  • 1 tsp prepared horseradish (or more to taste)
  • 1/2 tsp smoked paprika
  • 1/4 tsp garlic powder
  • 1 tsp lemon juice
  • Pinch of salt and pepper

Instructions
 

Instructions

  • Place a rimmed sheet pan on the middle rack and preheat the oven to 425°F (220°C).
  • Trim about 1/2 inch off the top of the onion, leaving the root intact, and peel the outer skin.
  • Set the onion root-side down and slice it into 4 quarters, stopping about 1/2 inch before the root.
  • Cut each quarter into 3–4 slices, again stopping before the root, to create 12–16 petals.
  • Flip the onion cut-side up and gently fan out the petals without tearing.
  • Whisk the eggs and buttermilk together in one bowl.
  • In a separate bowl, combine the flour, panko, kosher salt, smoked paprika, garlic powder, onion powder, black pepper, and cayenne.
  • Lightly dust the fanned onion with some of the dry mix, tapping to coat inner petals.
  • Hold the root and invert the onion into the egg-buttermilk mixture, spooning it between petals to coat thoroughly.
  • Transfer the onion to the dry mixture and shower it into all crevices, pressing gently to adhere; repeat wet and dry steps on sparse spots for a double coat.
  • Carefully remove the hot sheet pan, spray it, and drizzle a little oil where the onion will sit.
  • Place the onion root-side down on the pan, lightly drizzle or mist the petals with oil, and spray for even coverage.
  • Bake for 25–30 minutes until deep golden and crisp on the tips and the center is tender when pierced.
  • Let the onion rest for 5 minutes to set the crust before serving.
  • Stir together the mayonnaise, ketchup, horseradish, smoked paprika, garlic powder, lemon juice, salt, and pepper to make the dipping sauce and chill until serving.

Notes

Large sweet onions like Vidalia or Walla Walla work best. For extra adhesion, dust with dry mix before dipping, press crumbs gently, and chill the breaded onion 10 minutes before baking. Reheat leftovers at 375°F in an oven or air fryer for 6–10 minutes. For variations, try gluten-free flour and panko, add Parmesan to the panko, or use Cajun or ranch seasoning. Air fryer method: 360°F for 16–22 minutes, spraying lightly, until crisp and golden.