Peel and thickly slice the red onion into wedges. Halve the peppers. Scoop out the white bits and seeds. Slice it into thick chunks. Trim the courgette. Slice it into rounds about as thick as a £1 coin.
Chuck all the chopped veg in a bowl. Add the baby plum tomatoes. Add 2 tsp olive oil and some salt and pepper. Mix everything together to coat the veg in the oil and seasoning. Put to one side.
Chop the chicken into bite-size pieces. Put it in a separate bowl. Add 2 tsp olive oil and some salt and pepper. Turn a few times to lightly coat in the oil and seasoning.
Warm a large frying pan over a medium heat. Add the chicken. Fry for 8-10 mins, turning once or twice, till the chicken is browned all over and cooked through. Lift it out of the pan onto a plate.
Add the veg to the pan. Fry for 8-10 mins, stirring often, till the veg is soft and a little charred.
While the veg cooks, peel and grate or crush the garlic. Finely chop most of the basil leaves. Place both in a bowl and stir in 2 tsp olive oil and some seasoning to make a herby, garlicky sauce. The red basil’s stronger flavour makes it brilliant for sauces.
Add the chicken back to the veg pan. Cook and stir for 2-3 mins to warm the chicken through.
Divide the chicken pan-fry between two warm plates or bowls. Drizzle with the basil sauce and garnish with the saved basil leaves to serve.