Cut meat into 5-6 serving pieces and put it a casserole (yiouvetsi). Add butter, onion, peeled and diced tomatoes, salt and pepper. Mix well, cover and bake in a hot oven for 1 hour or until tender. Add 6 cups boiling water and manestra. Stir well. Cover and continue baking for 30 minutes, stirring occasionally. Serve at once with cheese. Makes 5-6 servings.