Step 1

Simmer: In a small saucepan, combine 2 cups chopped rhubarb, 1 cup water, and ⅓ cup granulated sugar. Cover with the lid slightly ajar and bring to a simmer over medium-low heat. Simmer until rhubarb is soft, 6 to 8 minutes, stirring occasionally. Add 1 cup chopped strawberries. Cook just until the strawberries soften, about 2 minutes.

Step 2

Strain: Set a fine mesh sieve over a heat-safe and freezer-safe container (see note 1). Strain the mixture, using a spoon to mash the fruit to extract as much juice as possible. Set aside the strained fruit for another use (see note 2). Stir in 1 tablespoon fresh lemon juice and ½ teaspoon vanilla extract.

Step 3

Freeze: Cover the container with a lid (or foil). Freeze until the mixture is partially frozen (slushy consistency), about 1.5 to 2 hours, then stir with a fork to break up the ice crystals and encourage it to freeze evenly. Return to the freezer. Freeze until hard, about another 2 hours. (You can stir it again, in between, if you remember!).

Step 4

Serve: Once frozen, scrape with a fork to create fluffy frozen ice. Spoon into bowls and serve immediately (see note 3).