Cut the mutton into 1 inch lengths. Slice the onions and chop the garlic, and fry to a golden colour in butter. Stir in the curry powder and salt, add 1 quartered tomato, 1 or 2 tablespoons of warm water and mix well, crushing the tomato with a spoon to extract the juice. Put in the pieces of meat and cook till well browned. Then cover with about a ¾ pint of hot water and simmer gently for about 1 to 1½ hours, adding more hot water if the sauce is too thick. Half an hour before serving add the rest of the tomatoes, peeled and finely chopped. Vegetables are sometimes added to meat curries.