Add the prunes to a bowl and cover with water. Soak for 30 minutes.
Add prunes to a blender using a slotted spoon. Blend, adding 1/3-1/2 cup water to make a smooth puree—or as much as desired to reach the desired consistency. (Adding more water will make a smoother puree, less a thicker one.) Use the stick that came with your blender, or stop and start as needed to help the mixture move around in the blender.
Serve or store.
To store in the fridge: Add to small airtight containers and refrigerate for 3-5 days.
To freeze: Add to a silicone ice cube tray and freeze overnight. Transfer frozen cubes to a zip top freezer bag and seal, removing as much air as possible. Freeze for up to 6 months.