Clean fresh fruit and cut up, or open bags of frozen fruit. Put all ingredients into a deep, large microwave-proof bowl. Leave plenty of room for boiling and expansion. Cover the bowl with microwave-acceptable plastic wrap. Heat on high power for 5 minutes, stir once, and then continue to cook at medium to low power until fruit is quite soft and has lost its shape. This may require 15 minutes or 30-40 minutes depending upon the power of your microwave and the degree of ripeness of the fruit. The ideal sauce will be chunky but not have any crispness left to the rhubarb. Allow to chill in the refrigerator, and serve in small dishes with cookies on the side.