beef stroganoff

1 lb round steak, cut into bite-size pieces OR pre-cut stew meat
1 can cream of mushroom soup
1/2 diced onion
2 tbsp butter
1/2 cup sour cream
1/2 cup water

Brown the meat in a skillet. Add the onion and cook until soft. Add the remaining ingredients then cover and let simmer, stirring occasionally, for 45 minutes. Serve over white rice or noodles.