Heat butter or margarine in wide pot. Add onions and saute until they brown lightly. Add spices and stir well. Add tomato paste and yogurt and cook 10 minutes. Add lamb, breaking it into fine mince with a wooden spoon. Make sure the mixture has no lumps. Bring to a boil, lower heat and cook 50 minutes. Add peas and simmer to heat through. Serve with naan or rice. Yield: 8 servings as part of a large meal.