In large microwavable bowl, place sweet potatoes and water. Cover loosely with paper towel. Microwave on High 13 to 18 minutes, stirring twice, until potatoes are fork-tender and can be mashed (bowl will be HOT; handle carefully). Drain potatoes; rinse with cold water, and drain thoroughly. With potato masher, mash potatoes well. Measure 2 1/4 cups of the potatoes, and set aside to cool. Reserve any remaining potatoes for another use.