Heat the oil in a large frying pan, add the chicken and cook, stirring, for 3–4 minutes until browned all over. Add the courgettes, aubergine, onion, green pepper and mushrooms and cook, stirring occasionally, for 15 minutes or until tender.
Add the tomatoes to the pan and gently stir. Stir in the garlic, bouillon powder, herbs and pepper and simmer, uncovered, for 5 minutes or until the chicken is tender. Serve immediately.