When should the thermometer be inserted — at the beginning of the cooking time or at the end? When you insert the thermometer will be determined by the type, oven-proof or instant- read. The important thing is to use a meat thermometer, no matter how the food is pre- pared — roasted, broiled, fried. • An oven-proof thermometer may be inserted into the food at the beginning of the cooking time and remain there throughout cooking. The temperature indicator will rise slowly as the food cooks