Measure yacon and raisins into a large cooking pot. Add water to a depth of about 1″.
Simmer over low heat for about an hour, stirring occasionally. You’ll notice that unlike apples, the yacon doesn’t break down; it remains firm enough that a simple potato masher just won’t do the trick.
Use an immersion blender to puree the cooked yacon right in the pot. If you don’t have an immersion blender, allow the yacon to cool and transfer to the bowl of a food processor. Pulse until you reach desired consistency.
Stir in cinnamon and honey. Chill and serve.
Yacon oxidizes very quickly — it’s totally normal for it to turn greyish when exposed to air.
The big question with this is whether or not it can be safely canned. I’ve yet to see a safety-tested recipe for doing so; until then I’ll stick with making it fresh or freezing it.