Step 1

Combine all of the ingredients in a medium sized pot over medium heat. Bring to a simmer, stirring frequently to prevent burning. Cook just until the rhubarb softens, about 5 minutes.

Step 2

Remove from heat and purée in a blender or with an immersion blender. If using a blender, do so in batches so the mixture doesn't overflow and burn you.

Step 3

At this point, you can either strain the purée by pressing it through a fine mesh sieve to remove any remaining fibers, or you can refrigerate it it straight away in a sealed container. If your rhubarb is older and fibrous, or if you don't want the odd streak of unblended fruit, then straining is for you. Otherwise, straining isn't necessary.

Step 4

Chill the purée for 2-3 hours, or until cold. Pour into the ice cream maker and churn according to the manufacturer's instructions. Transfer it to a 9"x5" loaf pan and freeze until firm and scoopable, about 3 hours. To serve, dip an ice cream scoop into a cup of very hot water, wipe dry and then scoop. Store in a sealed container in the freezer away from the door for up to 2 weeks.