The answer is sitting right on your countertop. Starting potatoes in the microwave gives them a bit of a head-start, so when they hit the pan they’re not fully raw. Microwaves cook food by heating up the moisture present inside them. Unlike the heat of the pan, which starts on the exterior and works its way into food, the microwave is heating evenly throughout the food — which is how it cooks food so fast. Adding potatoes that have been par-cooked in the microwave to a hot pan means that by the time they’re perfectly golden-brown on the outside, the center is also perfectly cooked — a feat that’s hard to achieve when you start with raw potatoes that are cooking from the outside in.