Melt butter in a large skillet over medium high heat. Saute bell pepper and mushrooms until tender, then stir in broth and flour and cook, stirring, until thickened. Add chicken, heat through and remove from heat.
In a small bowl combine sour cream, egg yolks, pimento, sherry, salt and pepper and mix together. Add this mixture to chicken mixture in skillet and heat thoroughly, stirring. Serve hot.