Air Fryer Blooming Onion
Air Fryer Blooming Onion
A blooming onion is one large onion cut almost through into petals, coated in seasoned flour and egg, then cooked until the outside is crisp and golden and the petals have splayed open like a flower. This version uses an air fryer instead of a deep-fryer, so there is no pot of hot oil to manage, just a generous, repeated spray of cooking oil to get the same crackling crust.
The onion itself does very little - it is sweet and soft once cooked, and its job is mostly to hold the coating and open up into a shape you can pull petals off. The coating is what carries the dish: a seasoned flour dredged onto the onion, dipped in egg, then dredged again, which builds a craggy, restaurant-style crust rather than a thin, floury one. Air-frying crisps this less aggressively than deep oil does, so spraying it well and re-spraying partway through the cook is what keeps the coating from turning out pale.
It comes out crisp on the surface, soft and slightly sweet inside, and gets its real character from the mayonnaise-based bloom sauce it’s dipped in - a mix of ketchup and horseradish with a little paprika and cayenne, sharp and a bit spicy against the sweet onion. It’s built as a shareable starter or party snack, pulled apart petal by petal straight from the basket, and doesn’t hold well once cooked, so it’s a dish to serve the moment it’s done rather than get ahead on.
Ingredients
Serves 4
The onion
- 1 large sweet onion (Vidalia), 350-400 g, peeled, root intact
- cooking oil spray, neutral (vegetable or canola)
The seasoned flour
- 125 g all-purpose flour
- 1 tbsp sweet paprika
- 1 tsp garlic powder
- 1 tsp salt
- ½-1 tsp ground cayenne pepper, to taste
- ½ tsp black pepper
- ½ tsp smoked paprika (optional)
- ¼ tsp dried oregano (optional)
- ¼ tsp dried thyme (optional)
- ¼ tsp ground cumin (optional)
The egg wash
- 2 large eggs
- 120 ml milk
The bloom sauce
- 110 g mayonnaise
- 2 tbsp ketchup
- 1-1½ tbsp prepared horseradish, creamy
- ½ tsp sweet paprika
- ¼ tsp ground cayenne pepper
- ⅛ tsp garlic powder
- 2 tbsp sour cream (optional)
- ½ tsp Worcestershire sauce (optional)
Directions
The onion
Cut about half an inch off the top of the onion and peel it, leaving the root end intact - that root is what holds the whole thing together once it’s cut into petals. Set the onion cut-side down and, starting about half an inch from the root, slice straight down toward it (not through it) at four evenly spaced points, then add three more cuts between each of those for sixteen petals in total. Turn it cut-side up, let it rest for a few minutes, then gently pull the petals apart and pick out any small loose pieces from the centre. If there’s time, soaking the cut onion in ice water for an hour or two helps the petals open further, though it isn’t essential - just drain and pat it dry afterwards if you do this.
Whisk the eggs and milk together in one bowl for the egg wash. In a second bowl, mix the flour with the paprika, garlic powder, salt, cayenne and black pepper, along with any of the optional smoked paprika, oregano, thyme or cumin.
Dredge the onion in the seasoned flour, working it down into the petals, then shake off the excess. Dip the whole onion into the egg wash to coat it fully, then dredge it through the flour a second time, again pushing it into the petals, and shake off any excess. This double coat is what gives the crust its craggy texture rather than a thin, flat one. Chilling the breaded onion for a while as the air fryer heats up can help the coating stick, if there’s time for it.
Preheat the air fryer to 350°F (175°C). Spray the onion generously all over with cooking oil, getting well into the opened petals, since the air fryer has no oil bath to crisp it and this spray is doing that job instead. Lower it into the basket cut-side up - a sling made from a strip of foil makes this easier - and air-fry for 20-25 minutes, spraying it with oil two or three more times as the petals open further, until it’s deep golden and crisp all over.
The bloom sauce
While the onion cooks, stir together the mayonnaise, ketchup, horseradish, paprika, cayenne and garlic powder for the bloom sauce, along with the optional sour cream and Worcestershire sauce if using. Refrigerate it until serving.
To serve
Lift the onion out with the foil sling and serve it right away, with the bloom sauce in the middle or in a bowl alongside for dipping.
Notes
The oil spray matters more than anything else here - without it the coating stays pale and floury, since air-frying doesn’t submerge the onion in fat the way deep-frying does. Spray generously at the start and again during cooking.
Cut-side up gives the classic look, with the petals splaying open like a flower as they cook. Cooking it cut-side down works too, but the result is more compact and less dramatic.
This doesn’t keep - the coating softens quickly once it’s off the heat, so serve it straight from the air fryer rather than making it ahead. If needed, the onion can be breaded and refrigerated before frying, but fry it the same day.
A single dredge (flour, egg, flour just once) gives a lighter, thinner coating if the full double-dredge crust is more than you want.
See Also
Beignet batter / tempura with fried meat, onion and other vegetables
