Wash pumpkin thoroughly, cut top off and clean out the inside.
Preheat oven to 350 degrees.
Sauté onion in oil, brown hamburger and drain excess oil. Add sautéed onions, soy sauce, brown sugar, mushroom and soup to hamburger. Simmer 10 min., stir occasionally.
Add rice and water chestnuts.
Spoon mixture into pumpkin, replace pumpkin top and set pumpkin on baking sheet. Lightly rub outside of pumpkin with oil. Bake for 1 hour. Serve on a platter and let everyone slice off as much as they want.
