Yes, some restaurants may warm up their plates in the microwave before serving your food. Warming plates can help keep the food at an optimal temperature for a longer period, ensuring that the dish doesn't cool down too quickly. It is a common practice in certain types of restaurants or for specific dishes where temperature plays a crucial role in the dining experience.
However, not all restaurants follow this practice, and it may vary depending on the cuisine and the restaurant's overall approach to food service. Some higher-end restaurants might use warming ovens instead of microwaves to keep plates warm, as they believe it provides a more consistent and even heat distribution.
If you have specific preferences or concerns about your food being served on warm plates, you can inquire with the restaurant staff beforehand. They should be able to let you know their approach to plate warming and accommodate any special requests if possible.