Place potatoes in an 8-inch square microwave-safe baking dish. Cover with a lid or plastic wrap. (If covering the dish with plastic wrap, poke a small hole in the plastic.)
Microwave on HIGH for 8 minutes or until the potatoes are tender when pierced with a fork.
Use oven mitts or pot holders to remove the dish from the microwave; pour the potatoes into a large bowl.
Add the chiles, sour cream, cheese, cumin, and salt. Mash with a potato masher or an electric mixer at medium speed until fairly creamy. Stir in the tomato. |