This could not have been easier. Start with very ripe sour -- not sweet -- cherries. Remove the stems, then cut each cherry in half and remove the pit. Dump into a pot, add a few tablespoons of water, and turn the stove onto medium heat. As it thickens, stir and add sugar to taste. Serve hot over cold yogurt or ice cream.
You can do this with pretty much any fruit; it's a great way to use fruit up when it's getting over-ripe. My roommate Eva and I whipped this up in a few minutes to satisfy a week night sweet tooth. Obviously, it can be made healthier by using low-fat or non-fat yogurt.