I boil them for a few minutes, not too long, until they are plumper and floating. Then I puree them with a few spoonfuls of the cooking water. I mix one ounce with an ounce of pureed dried apricots (cooked the same way) and an ounce or two of pear or plum puree. And, often I just add a half ounce of the prune puree to whatever other breakfast puree DS is having. He actually really likes the taste and it can help sweeten an apple of plum that is a bit sour.