In a large saucepan or Dutch oven brown beef or pork, half at a time, in hot oil. Drain fat from pan. Return beef or pork to saucepan. Stir in the 2-1/2 cups water, onion, dry sherry, 3 tablespoons soy sauce, ginger, and sugar. Bring to boiling. Reduce heat and simmer, covered, for 1 to 1-1/4 hours for beef (about 30 minutes for pork) or until meat is nearly tender.
Stir in broccoli, carrots, red or green sweet pepper, and water chestnuts. Cover and simmer about 10 minutes more or until meat and vegetables are tender.
Stir together the 1/4 cup water and the cornstarch; stir into soup. Cook and stir until thickened and bubbly. Cook and stir for 2 minutes more. If desired, serve with additional soy sauce. Makes 4 servings.