Heat 2 Tbsp oil in a large saucepan and fry the small onions for 10 minutes or until golden brown. Remove and set aside. Add the remaining oil and fry the bay leaves, cardamoms, cloves, chilies and peppercorns for 2 minutes. Add the chopped onions, garlic and ginger and fry for 5 minutes. Stir in the ground spices and salt and cook for 2 minutes. Add the tomatoes and the water and simmer for 5 minutes until the sauce thickens. Add the chicken and cook for about 15 minutes. Return the reserved small onions to the pan, cover and cook for a further 10 minutes or until the chicken is tender. Serve with plain rice.