Storage: Filet mignon tastes best right after it has been cooked and rested, but if you have leftovers, it is possible to store and reheat it. To store, use a small airtight storage container or tightly wrap your leftover filet in plastic wrap to keep it from drying out and keep it in the refrigerator. To reheat, place your leftover steak in a baking dish and cover with aluminum foil. Place in a 250°F oven and allow the steak to warm gently until the internal temperature reaches at least 110°F. Leftover filet mignon will last up to 3 days in the refrigerator.