In a heavy kettle ( at least 5 quarts) cook bacon over moderate heat, stirring, until crisp. Add onions and cook, stirring, until softened. Peel potatoes and cut into 3/4-inch cubes. Add potatoes, celery, broth, and water and simmer, covered, 10 minutes. Add lima beans and corn and simmer, covered, 5 minutes.
In a small bowl dissolve cornstarch in half -and-half or milk and stir into simmering soup with Worcestershire sauce. Bring soup to a boil, stirring, and add fish. ( If using smoked trout, no further cooking is necessary; if using finnan haddie or fresh fish, simmer, covered, 5 minutes, or until it just flakes.) Stir in parsley or dill. Soup may be made 2 days ahead (cool uncovered before chilling covered). Reheat gently.
Recipe courtesy of Gourmet Magazine