In a saucepan combine :
1 c. wild rice, 1 Tbls. butter, and 2 c. water. Place over high heat and bring to a boil. Reduce heat, cover and simmer for 50 minutes, or until water is absorbed and rice is tender.
1 large diced onion with 2 Tbls. butter. Set aside. In the same pan, cook 1 lb. mild pork sausage.
In a large bowl, combine the cooked rice, sausage, onions, and 1 c. diced celery, 1- 8 oz. can sliced water chestnuts, and 1 green pepper, diced. Stir in 1 can cream of mushroom soup.
Place mixture in a lightly greased 9x13 pan. Bake at 350 F, uncovered for one hour.