A roaster oven not only cooks, but also reheats food. The large capacity of some roaster ovens lets you reheat and serve food for a party straight from the oven. When you think of your roaster oven in the same way you do a conventional oven, you will realize this small kitchen appliance's versatility. Take the internal temperature of the food after it reheats to ensure that the food has reached a high enough temperature to kill food-poisoning-causing bacteria.
Preheat the roaster oven to 325 degrees Fahrenheit.
Place the roasting rack into the bottom of the roaster if using a casserole or baking dish to hold the leftovers during reheating.
Once the roaster has preheated at least 20 minutes, place the baking dish with the food onto the baking rack or put the food directly into the cooking portion of the roaster oven.
Cover the roaster oven, removing only to stir the food every 10 to 15 minutes.
Insert a meat thermometer into the thickest portion of the dish and turn the heat down to low or warm on the roaster oven when the food registers at least 165 degrees.
Serve the food with the roaster on the warm or low setting, testing periodically with the food thermometer and stirring.
Re-cover with the roaster lid and turn the heat back up to 325 if the food's temperature drops below 140 degrees. Return the food to 165 degrees as soon as possible.
Discard any food that remains at 140 degrees or below for more than two hours.