Pre heat oven to 180°C / 375°F / Gas mark 4.
In an oven proof dish, place chicken, onion, pepper, orange juice, celery and potatoes.
Season lightly and cover with tin foil.
Bake for 30 minutes until chicken is thoroughly cooked and potatoes soft.
10 minutes before final cooking time, add cornflour and water. Stir and replace in oven.
When cornflour looks clear and the sauce thickened, the dish is ready.