Refrigerate leftover stuffed peppers within 2 hours and keep them in a tightly covered container for up to 4 days. You can also freeze each cooled pepper individually for up to 2 months. Wrap them snugly and freeze without fresh cilantro so the garnish doesn't darken. To reheat, cover and bake at 350°F for 15 to 18 minutes or until the center reaches 165°F. Add fresh cilantro after heating. Discard any pepper with a sour smell, slimy surface or leaking filling that looks unusually watery.