Sprinkle chicken lightly with flour. In a large skillet, melt the butter over medium high heat. Cook chicken until browned all over, about 5 minutes on each side. Reduce heat to medium and cook for 10 minutes longer on each side. Remove from pan and keep warm. Add onions and mushrooms to the skillet and cook, stirring often, until tender, about 5 to 10 minutes. Stir in water and bring to a full boil, loosening any brown bits from the bottom of the pan to flavor the sauce. Remove from heat and stir in yogurt and salt and pepper to taste. Return chicken to the pan and spoon sauce over it.

Makes 6 servings.