Place beef, fat side up, on rack in a roasting pan. Season with salt and pepper; top with onion slices. Add enough water to pan to cover the bottom. Bake at 350° for 3-1/2 hours or until tender. For gravy, mix flour with water; stir into pan drippings, cooking over medium heat until gravy has thickened.
First Day: Pot Roast. Place peeled carrots and halved peeled potatoes in with the roast during the last 1-1/2 hours of cooking.
Second Day: Sweet-and-Sour Beef. Heat chunks of leftover beef in sweet-and-sour sauce and serve over cooked noodles. To make sauce, saute 1/2 cup chopped celery and 1/4 cup chopped onion in 2 tablespoons butter until tender. Stir in 1 tablespoon flour. Add 1/4 cup sugar, 1/4 cup vinegar and 1/4 cup water. Stir until slightly thickened.
Third Day: Beef Stew. Heat gravy and chunks of beef in a pan, along with leftover potatoes and carrots.
Fourth Day: Beef over Rice. Heat leftover beef and gravy and serve over cooked rice.
Fifth Day: Meat Pie. Place leftover meat chunks, gravy, peas and carrots in pie plate. Top with you favorite pie crust or biscuits. Bake at 350° for 30-45 minutes or until crust is golden.