Prick the potatoes all over with a fork and place on a plate. Cook in the microwave oven for 8 minutes, turning over once, until tender when pierced with the tip of a knife. Let sit for 5 minutes. Cut the potatoes in half, scoop out the flesh with a spoon and place in a large bowl. Coarsely mash with a fork. You will need 2 cups (500 ml) of mashed potatoes.