The main ingredient in a turkey sandwich is turkey meat, which is sliced and placed between slices of bread. Turkey is a popular choice due to its lean protein content and lower fat compared to other meats. It is often seasoned or smoked to enhance its flavor. Additional ingredients might include lettuce, tomatoes, cheese, and condiments like mayonnaise or mustard, which add flavor and texture. Turkey sandwiches are favored for their versatility and can be served hot or cold, making them a staple in lunch menus.