Air Fryer Recipe
Caramelized Red Onion and Blue Cheese Tart
A tempting and easy-to-make caramelized red onion and blue cheese tart recipe, perfectly suited for air frying.
Ingredients
- 1 sheet of ready-made puff pastry
- 2 large red onions, thinly sliced
- 2 tablespoons of olive oil
- 1 tablespoon of balsamic vinegar
- 100g blue cheese, crumbled
- 1 tablespoon of fresh thyme leaves
- Salt and pepper, to taste
- 1 egg, beaten (for glazing)
Method
- Preheat air fryer to 180°C. Roll out puff pastry on a floured surface and transfer to parchment paper. Create a border by folding edges.
- Heat olive oil in a pan over medium heat. Add onions and cook until soft. Add balsamic vinegar and cook until caramelized. Season with salt and pepper.
- Spread caramelized onions over puff pastry, staying within the border. Crumble blue cheese over onions and sprinkle with thyme. Brush edges with beaten egg.
- Transfer tart with parchment paper to air fryer basket. Cook for 15-20 minutes until pastry is golden and cheese is bubbly.
Why this works in an air fryer
Air fryer convection drives moisture from the puff pastry quickly, so the laminated butter layers lift before the onion topping can make the base soggy. Pre-caramelising the onions removes water and concentrates sugars, while the blue cheese melts into the onion layer rather than needing long oven-style baking.
Equipment notes
Assumes a basket of about 20 x 20cm or a tart trimmed to fit with airflow around the edges; in a single-drawer air fryer cook on the lower rack/basket base and check at 15 minutes, while dual-zone models often run slightly less forcefully per drawer, so use one zone only if possible or add 2-4 minutes and rotate the tart halfway.
Common pitfalls
- Pale, soft base under a browned top? The onion mixture was too wet or piled too thickly; cook the onions until jammy with no loose liquid, then use a thinner layer next time.
- Pastry edges rising but the centre looks dense and greasy? Too much cheese has pooled fat in the middle; reduce the blue cheese slightly or scatter it more evenly, leaving small gaps for steam to escape.
- Edges browning hard by minute 10 while the centre is still pale? The tart is too close to the heating element or the fryer runs hot; drop to 170°C and cover the rim loosely with a narrow strip of foil if needed.
- Parchment lifting into the fan or singeing at the corners? It is oversized or not weighted by the pastry; trim it close to the tart outline before cooking and keep it below the basket rim.
Variations & substitutions
- Use goat's cheese instead of blue cheese for a milder tart; it browns less aggressively, so expect a paler, creamier topping rather than bubbling blue-cheese pockets.
- Swap red onions for shallots for a sweeter, softer filling; they cook down faster in the pan, so start checking for caramelisation a few minutes earlier.
- Add sliced pear after the onions are spread on the pastry; keep the slices thin so they soften in the 15-20 minute air-fryer window without leaking too much juice.
- Use wholegrain mustard brushed thinly over the pastry base before adding onions; it adds sharpness but can slow base crisping if applied thickly, so use no more than a teaspoon or two.
Storage & reheating
Keep leftovers chilled for up to 3 days, then reheat in the air fryer at 160°C for 4-6 minutes until the pastry re-crisps and the cheese is warmed through.
Nutrition
Calories: 250
