Meanwhile, in 2-quart saucepan, melt butter over medium heat. Add onion; cook about 2 minutes, stirring occasionally, until tender. Add flour, salt and pepper; stir until well blended. Gradually stir in broth; cook and stir until bubbly and thickened. Stir in chicken, black beans, green chiles and corn. Simmer about 5 minutes or until hot.