In a large saucepan, heat oil until hot. Add mushrooms, onion and celery. Cook and stir until vegetables are tender, about 8 minutes. Stir in chicken broth, corn kernels, creamed corn and ham. Bring to a boil, reduce heat and simmer covered to blend flavors, about 15 minutes. In a small bowl, whisk together milk and flour until smooth, stir into saucepan. Return to a boil, cook and stir until chowder thickens slightly. Season with hot pepper sauce if desired. Serve immediately. Posted to EAT-L Digest by Sue Albro <SALBRO@OCMVM.CNYRIC.ORG> on Feb 12, 1998