Preheat oven to 375 degrees F (190 Degrees C). Cut off top of pumpkin, scrape out seeds and pith.
In a large deep skillet, saute vegetables in 1/4 cup shortening until soft. Add beef; cook and crumble until evenly brown. Add the pepper, ketchup, garlic, salt, Worcestershire sauce and tomato sauce. Simmer 15-20 minutes.
In a large mixing bowl, combine 2 cups of the beef mixture, soy sauce, mushrooms, brown sugar, soup and rice. Mix well, pour into pumpkin and replace lid. Cover and freeze remaining beef mixture.
Place filled pumpkin on a baking sheet and bake for one hour or until pumpkin is tender. As you serve dinner, be sure to scoop out a little of the cooked pumpkin too.