Leftover turkey is a fact of life during the holidays, but reheating lean breast (Sliced turkey should be warm throughout; if the slices are relatively thick, you can. Preheat oven to *. 2. Place the Turkey Breast in a shallow pan with a small amount of liquid (water or turkey drippings) 3. Cover in foil and heat approximately 15 minutes per pound, until the internal tem- perature reaches *.