Raspberry Chicken
["2 lb. boneless, skinless chicken breasts", "2 Tbsp. butter", "1 onion, chopped", "1/4 to 1/2 c. raspberry vinegar", "1/4 c. chicken broth"]
["Melt butter and brown chicken on both sides over medium-high heat.", "Remove from skillet.", "Add onion to the drippings in the pan and cook, covered, over low heat until tender, about 15 minutes. Add vinegar; raise heat and cook, uncovered, until vinegar is reduced to a syrupy spoonful.", "Whisk in chicken stock and simmer about 1 minute.", "Return chicken to skillet and simmer gently in sauce, basting often, until done.", "Serves 2 to 4."]
["chicken breasts", "butter", "onion", "raspberry vinegar", "chicken broth"]