These onion bombs seal a seasoned beef and mozzarella meatball between two curved onion layers, so the onion steams the meat juicy while the bacon on the outside crisps into a smoky shell. Blitzing the mozzarella to fine crumbs matters: it spreads through the beef instead of pooling in one molten pocket, so every bite gets cheese. Twenty minutes in the air fryer at 180°C (350°F) cooks four bombs the size of a small orange; look for deep golden bacon and an internal temperature of 74°C (165°F). While they cook, ketchup, brown sugar, rice vinegar, and soy sauce simmer into a tangy dip for serving.
Instructions
- 1
Slice off the onion tops and bottoms, cut each in half, and peel off the skin. Separate the layers into half shells — you need 8 pieces (4 pairs).
- 2
In a bowl, combine ground beef with paprika, salt, and black pepper.
- 3
Blitz the mozzarella in a blender into fine crumbles. Add to the meat mixture and mix thoroughly until every bite has cheese and spice throughout.
- 4
Shape the meat into balls roughly the size of a small orange — big enough to fit inside the onion shells.
- 5
Nestle each ball into an onion half, then cap it with another half on top. Press together firmly.
- 6
Wrap each onion bomb crosswise with 2 slices of bacon to hold everything together.
- 7
Air fry at 180°C / 350°F for 20 minutes until the bacon is golden and the meat is cooked through.
20:00 - 8
While the bombs cook, make the sauce: combine ketchup, brown sugar, cornstarch, rice vinegar, soy sauce, and water in a saucepan. Bring to a simmer, stirring occasionally for 2–3 minutes until thickened. Transfer to a dipping bowl.
03:00 - 9
Serve the golden onion bombs with the sweet and sour sauce on the side. Dunk and enjoy.
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Notes from our kitchen
We use the larger outer onion layers for the shells; the small inner ones will not close around a meatball the size of a small orange, and any gap lets melted mozzarella leak into the basket before the bacon can seal it. Pressing the two halves together firmly before wrapping matters more than it looks.
At 180°C (350°F) we watch the bacon rather than the clock: once it turns deep golden and loses its rubbery look at the seams, the beef inside is done. Rushing the sauce is the other trap. Stir the cornstarch into the cold mixture before it heats, or it seizes into lumps at the simmer.
Variations
- Oven method. No air fryer? Bake the bombs on a wire rack over a tray at 200°C (400°F) for about 30 minutes, until the bacon is crisp and the beef reaches 74°C (165°F) inside.
- Cheese swap. Cheddar or smoked gouda works well in place of mozzarella. Grate it finely so it blends through the beef the same way the blitzed mozzarella does.
- Meat swap. Ground pork, or a half beef and half pork mix, works well here. Keep the balls the same size so the 20-minute timing still holds.
- Make ahead. Assemble and bacon-wrap the bombs up to a day ahead. Keep them covered in the fridge and air-fry straight from cold, adding a few extra minutes.
Frequently Asked Questions
How do I get the onion shells?
Halve and peel onions, then separate the layers into curved half-shells. The bigger outer layers cup the meatball; pair two to enclose each bomb.
How do I stop them falling apart?
Press the meatball firmly between two onion halves, then wrap snugly with two crossed bacon slices — the bacon holds everything together as it crisps.
Do the bacon slices need toothpicks to stay on?
Not in the air fryer. Wrap the two slices crosswise so each one passes over both onion caps, and tuck the ends underneath the bomb; the basket keeps them in place and the bacon tightens as it renders. If a slice keeps slipping, one toothpick through the top holds it.