Preheat the oven to 180°C.
Add the chicken, onions, and peppers to an ovenproof dish. Spray with low-calorie cooking spray.
In a small bowl, combine the remaining ingredients and mix until smooth. Pour over the chicken and vegetables, then mix to coat.
Pop in the oven and cook for 40 minutes, until the chicken is browned and cooked through. You may need to add a couple of tablespoons of water to the dish to make some extra sauce — it really depends on how much liquid comes out of the vegetables and chicken during the cooking process.
Serve with rice and a wedge of extra lemon!