Add the chicken pieces to the pan and brown on all sides. Return the vegetables to the pan and add the wine, stock, tomatoes, bay leaf and seasoning to taste. Bring to a boil, then cover and simmer for 40 minutes or until the chicken is cooked.
Melt 1 tbsp of the butter with the oil in a saucepan and fry the garlic, leeks and spring onions until softened. Stir in the mushrooms and fry for a further 2 minutes. Remove the vegetables from the pan with a slotted spoon.