Cut the pumpkin in half lengthwise, discarding seeds and membranes. Place pumpkin halves, cut sides down, in a baking dish, and add 1/4 cup water to the dish. Cover with heavy-duty plastic wrap, and vent. Microwave at high 10 minutes (or about 5 minutes per pound) until pumpkin is tender when pierced with a fork. Cool slightly, and scoop out filling.