Preheat oven at 200 degrees.
In a large bowl, mix 1 tbsp olive oil, salt, pepper and garlic. Marinate the chicken in the mixture for 30 minutes.
In a large ovenproof dish, place the chicken, onion and lemon wedges and bake for 20 minutes.
In a bowl, mix the green beans, red pepper and remaining olive oil together.
Add the green bean mixture to the partly cooked chicken and bake for an additional 20 minutes or until chicken is thoroughly cooked.