Dredge chicken breast halves in flour, salt and pepper. Melt olive oil and butter in skillet. Cook chicken, turning once until lightly browned and juices run clear, about 15 minutes. Remove chicken to platter, keep warm. Add garlic to skillet, mix in tarragon, mustard, wine and broth. Cook over high heat for 1 minute. Remove from heat, stir in sour cream. Season with salt and pepper. Pour sauce over chicken.
4 servings