Preheat the oven to 200 °C (180 °C fan) and line a baking tray with baking paper.
Cut the chicken breast into strips. Deseed the peppers and cut them into strips, and cut the red onion into wedges.
Put the chicken breast, peppers and red onion in a large bowl. Mix thoroughly with the olive oil, fajita seasoning and sea salt until everything is evenly coated.
Spread the mixture out flat on the baking tray so the chicken breast and veg roast evenly.
Cook at 200 °C for 15–20 min, until the chicken breast is cooked through and the peppers and red onion are lightly browned at the edges.
To serve, cut the lime and squeeze the juice over the hot chicken fajita traybake. Serve straight away.
Good to know
A traybake like this saves exactly those evenings when things need to be quick. Little washing-up, lots of flavour, and in the end something honest on the table.
Swaps
Chicken breast → skinless chicken thighs (often juicier, with a little more iron) | Red onion → spring onions (milder in flavour) | Peppers → courgette (slightly fewer carbs) | Olive oil → avocado oil (stable at high heat and mild)
Allergens
The recipe is naturally free from gluten and milk, as long as the fajita seasoning contains no additives. Season mildly for children; during pregnancy cook the chicken all the way through.