Peel onions. Trim excess fat off meat. Toss meat in flour seasoned with salt and pepper. Heat drippings or oil in heavy casserole pan and brown meat. Add tomatoes with juice and mustard, blending well. Add remaining ingredients. Stir well. Cover and simmer for 2 1/4 to 2 1/2 hours until meat is tender. Serve with Oatmeal Biscuits. Yield: 4-6 servings.