1Put cherries in a 4-cup measure. Microwave with 650 watts until cherries start to split, 3 to 4 minutes. Let stand until cherries are comfortably cool to handle, about 5 minutes. Remove and discard pits, saving any juices. Coarsely chop cherries.
2Put cherries and juices back in 4-cup measure. Add remaining ingredients. Cover tightly with plastic wrap. Microwave with 650 watts until fruit is soft, stirring twice, 4 to 5 minutes. Sauce will be chunky.