This recipe for crispy onion petals with a copycat Outback bloomin' sauce has been a party favorite in my house for years. I first put it together one rainy weekend when I wanted something indulgent and shareable that would make everyone linger at the table. The relationship between a sweet, tender onion center and a crunchy seasoned batter is pure comfort — every bite gives you that contrast of soft and crisp that the whole family fights over. The sauce, a creamy, slightly spicy blend of mayo, sour cream, ketchup and horseradish, cuts through the richness and keeps each mouthful bright and addictive.

I discovered this exact combination after reverse-engineering the flavors I remembered from a restaurant appetizer. It took a couple of tries to get the batter crisp without overcooking the onion. Now I time the oil, rest the coated petals on a rack, and double-coat key pieces for a perfect golden shell. These are best eaten warm, right after frying, but the sauce and a quick reheat will resurrect leftovers beautifully. This dish is exceptional for gatherings, game-day spreads, or a nostalgic night in when you want something a little extra.

Ingredients

• Mayonnaise (1/2 cup): Use a full-flavor brand (Hellmann's/Best Foods or Dukes) for the best sauce creaminess — low-fat versions thin out the texture and mute the tang.
• Sour cream (1/4 cup): Adds tang and body to the sauce; choose a regular style for richness or a cultured variety for subtle tang.
• Ketchup (2 tablespoons) and Prepared horseradish (2 tablespoons): Ketchup provides sweetness and color while horseradish brings the signature bite; use refrigerated bottled horseradish and taste as you go.
• Sweet onion (1 large): Vidalia or any large sweet onion is ideal for a slightly sweet flavor and tender layers; white or yellow onions work if sweet aren't available.
• All-purpose flour (2 cups): The base for the dry mix — spoon and level for accurate measurement; adding a 1/4 cup cornstarch in place of part of the flour can make an even lighter, crispier crust.
• Seasonings (various teaspoons): Seasoned salt, black pepper, garlic powder, cayenne, onion powder and smoked paprika build a layered, savory crust — buy fresh jars and shake before measuring.
• Buttermilk (1 cup) and 1 large egg: Buttermilk tenderizes and helps the batter cling; if you don't have buttermilk, sour milk (1 cup milk + 1 tablespoon vinegar, let sit 5 minutes) works in a pinch.
• Oil for frying: Use a neutral oil with a high smoke point like peanut, canola or vegetable oil and maintain 350°F for consistent frying.

Instructions

Make the Bloomin' Sauce: Whisk together 1/2 cup mayonnaise, 1/4 cup sour cream, 2 tablespoons ketchup, 2 tablespoons prepared horseradish, 1 minced garlic clove, 1/2 teaspoon kosher salt, 1/4 teaspoon black pepper, 1/4 teaspoon smoked paprika and a pinch of cayenne until smooth. Cover and chill at least 30 minutes to let the flavors marry; making it the day before improves depth. Prepare the Onion: Trim the root, remove the peel, and halve the onion through the root. Cut each half into quarters, then slice the quarters in half so you have petals that separate into layers. Keep the root intact while cutting to help the layers stay together until you separate the petals by hand just before coating. Mix Dry and Wet Bases: In a large bowl combine 2 cups flour, 2 teaspoons seasoned salt, 1/2 teaspoon black pepper, 1/2 teaspoon garlic powder, 1/2 teaspoon cayenne, 1/2 teaspoon onion powder and 1/2 teaspoon smoked paprika. In another bowl whisk 1 cup buttermilk with 1 large egg until smooth. Dry-Coat the Petals: Separate petals and put them in a gallon zipper bag with 1/4 cup of the flour mixture. Seal and shake to dust the petals; this initial dry coat helps the wet batter cling and prevents slippage during frying. Tap off excess flour before dipping into the buttermilk mix. Double-Coat for Crunch: Working in handfuls, dip the floured petals into the buttermilk-egg mixture, let excess drip, then transfer back to the flour bowl and toss to fully coat. Shake off extra flour and place the coated pieces on a parchment-lined sheet tray. Repeat until all petals are coated. Heat Oil and Fry: Heat 2 inches of oil in a deep fryer or large heavy skillet to 350°F. Fry petals in small batches to avoid overcrowding — 3 to 4 minutes per batch or until golden brown and the onion inside is tender. Use a thermometer to keep oil steady and a slotted spoon to remove petals. Drain and Rest: Drain on paper towels briefly, then transfer to a wire rack over a sheet tray; this prevents sogginess. Once all batches are fried, serve immediately with chilled bloomin' sauce.

Storage Tips

Store leftover petals in a single layer on a wire rack inside the refrigerator, loosely covered with foil to avoid condensation. They will keep for up to 2 days, though texture is best the day they are made. For longer storage, flash-freeze on a tray, then move to an airtight freezer bag for up to 3 months. Reheat from frozen in a 400°F oven for 8 to 12 minutes, flipping midway, until the exterior is crisp and the interior warmed through. The sauce stores separately for up to 3 days in the fridge.

Ingredient Substitutions

If buttermilk is unavailable, create a quick substitute with 1 cup milk plus 1 tablespoon vinegar or lemon juice — let it rest 5 minutes. For a lighter crust, replace 1/3 cup of flour with cornstarch. Use Greek yogurt in place of sour cream in the sauce for a tangier finish and thicker texture. For a gluten-free option, choose a 1-to-1 gluten-free flour blend and add 2 tablespoons rice flour for extra crunch. Be mindful that flavor and texture will vary slightly with each swap.

Serving Suggestions

Serve petals hot with a generous bowl of the bloomin' sauce and a second dipping option like ranch or a spicy aioli. They pair beautifully with crisp salads, grilled meats, or as part of a tapas-style platter. Garnish with chopped chives or parsley for color and a squeeze of lemon if you want extra brightness. For a party, present them in a large shallow bowl or on a wooden board with small ramekins of sauce scattered for easy grabbing.

Cultural Background

Fried battered onions are a popular bar and restaurant appetizer across the United States, with variations from onion rings to the dramatic "bloom" style popularized by casual dining chains. The idea of battering and frying vegetables can be traced to many cuisines, but the American take emphasizes sweet onions, bold seasonings and shareable presentation. This version riffs on the signature bloomin' sauce flavor profile — creamy, tangy and slightly spicy — that complements fried textures and became a staple of comfort-oriented menus.

Seasonal Adaptations

In summer use local sweet onions for peak flavor and serve with a chilled sauce. For winter, add warming spices to the flour mix like a pinch of cumin or smoked chili powder for depth. During the holidays, serve smaller petals as part of an appetizer board with roasted nuts and pickled vegetables to cut through the richness. You can also bake the petals at 425°F on a greased sheet for 12 to 15 minutes for a lower-oil option, flipping once for even color.

Meal Prep Tips

Prep the sauce and store in the refrigerator up to 3 days ahead. Cut the onions and separate petals, then keep them wrapped and refrigerated for up to 24 hours; coat and freeze ahead of time for easy frying on the day of your event. Label freezer bags with date and fry straight from frozen, adding an extra minute or two per batch. Use a thermometer and preheated oil to keep frying times consistent and ensure every batch is uniformly golden.

These onion petals bring people together — whether for an impromptu weeknight treat or a planned gathering. The crunchy coating, sweet onion, and tangy-spark of sauce make them impossible to ignore. Try making them once, then tweak the spice to make them your signature party food; you'll be asked for the recipe before the plate is empty.