Onions in the Air Fryer
Frying onions in a pan means standing over them, stirring, and still ending up with some burnt and some raw. Air fryer onions need only a few shakes of the basket, and 15 minutes later you have soft, sweet, golden onions for burgers, hot dogs, sausages or curry bases. The same method also gives you crispy onions and whole roast onions with small changes.
- Temperature
- 180°C
- Total time
- 23min
- Prep
- 8min
- Servings
- 4
- Per serving
- 75kcal
Why the air fryer works for onions
Frying onions in an air fryer works because the hot air dries the surface of each slice while the inside softens. In a frying pan, onions release water and spend the first ten minutes stewing before they brown. In the basket the steam escapes at once, so the slices go from soft to golden in a single step. If you ever wondered whether you can fry onions in an air fryer, the answer is yes, and the results are more even than you would expect.
Air fryer onions also need far less oil than the pan, and there is no pan to scrub. That makes a big batch easy, whether you want a topping for burgers or a base for a curry, chilli or bolognese. This page covers the plain, soft sort. For whole roast onions, see roasted onions.
How to cook onions in the air fryer
Tap a time to start a timer.
- Slice evenly Peel the onions, halve them from root to tip and cut into half-moons about 5 mm thick. Even slices are more important than the thickness, because thin and thick pieces will not finish together.
- Season Toss the onions in a bowl with the oil, salt, sugar if using, and pepper. Separate the layers with your fingers so every slice is lightly coated.
- Cook Preheat the air fryer to 180 °C for . Tip in the onions and cook for , shaking or stirring after 5 and . Pull apart any slices that clump together.
- Check the colour After start checking. The onions are ready when they are soft, with golden brown edges. For darker, more caramelised onions add , but watch the thinnest slices as they burn first.
- Serve Spoon the onions straight onto burgers or sausages while they are hot, or let them cool and keep them for the week.
Cooking times and temperatures
| Onions | Temperature | Time |
|---|---|---|
| Sliced onions, 5 mmStir twice | 180 °C | 15 min |
| Crispy onions, thin slicesToss in flour (not gluten-free) | 180 °C | 8–10 min |
| Caramelised onionsStir every 7 minutes | 160 °C | 25–30 min |
| Onions and peppersPeppers cut to same size | 180 °C | 12–14 min |
| Halved onions | 180 °C | 25 min |
| Whole medium onions | 180 °C | 35–40 min |
Times are a guide and depend on the size of the food and the power of your air fryer. See also cooking times and temperatures for all dishes.
Tips
- Cut the slices the same thickness. A sharp knife gives you a flat, even slice, and a mandoline (with its guard) is even better. Aim for 5 mm for soft onions or 2 mm for crispy ones.
- Use red onions for sweetness. Red onions soften to a sweeter, darker result, while brown onions give a stronger, more savoury flavour.
- Do not salt too early. Salt pulls out water within minutes, which makes the slices soggy. Toss the onions with salt just before they go in the basket.
Serving
Spoon the onions over burgers and hot dogs, fold them through scrambled eggs, or pile them next to sausages and mash for an easy dinner. Soft onions from an air fryer are also a quick base for gravy. For a whole-onion side dish, see the variations below, or try roasted peppers cooked in the same basket.
Storing and reheating
Cooked onions keep for up to 4 days in a covered container in the fridge, and for 3 months in the freezer. Reheat them in the air fryer at 160 °C for 3–4 minutes, until they are steaming hot all the way through (75 °C). If you plan to batch-cook air fryer onions, spread them out on a tray to cool before you box them, so they do not stick together.
Variations
- Onions and peppers: Add 2 sliced peppers with the onions and cook at 180 °C for 12–14 minutes for fajitas or hot dogs.
- Roast whole onions: Rub medium onions with oil, cut a cross in the top and cook at 180 °C for 35–40 minutes until soft in the centre.
- Balsamic onions: Stir 1 tbsp balsamic vinegar through the onions for the last 3 minutes. They turn sticky and dark, ideal for cheese toasties.
Troubleshooting
- The onion slices are burnt at the edges but pale in the middle
- The slices were uneven or the basket was packed too deeply. Cut slices of one thickness, keep the layer under 3 cm deep and stir more often towards the end.
- The onions are soft but not golden
- They need more time or a little more oil. Add 2–3 minutes, and make sure the onions were not wet from rinsing or from a damp chopping board.
- The onions smell sharp and taste raw
- Thick slices from a very large onion can stay firm in the middle. Cut them thinner or give them 3–4 minutes more.
Frequently asked questions
Can you cook onions in an air fryer?
Yes. Sliced onions cook very well in an air fryer basket, and roast whole or halved onions are easy too. Slices take 15 minutes at 180 °C.
Can you fry onions in an air fryer without oil?
You can, but they dry out and brown unevenly. One tablespoon of oil for three onions is enough to get them soft and golden, and a spritz from an oil spray works as well.
How long do whole onions take in the air fryer?
A medium whole onion needs 35–40 minutes at 180 °C. Halve it and it is done in about 25 minutes. The centre should feel soft when a knife goes in.
How do you make crispy onions in the air fryer?
Slice the onions very thinly, toss them with 1 tbsp plain flour and 1 tsp oil, then cook at 180 °C for 8–10 minutes, shaking every 3 minutes, until brown and crunchy. The flour means this version is not gluten-free.
Can you caramelise onions in the air fryer?
Yes. Cook sliced onions at 160 °C for 25–30 minutes with 1 tsp sugar and a knob of butter (not dairy-free or vegan, so use oil instead if needed), stirring every 7 minutes. Add a splash of water if they catch.
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