Recipe from Oasis at Bird-in-Hand:

Ingredients

• ½ cup sugar
• ½ lb. rhubarb, trimmed and cut into 1" pieces
• 1 cup sliced strawberries, plus more for garnish
• 3 tbsp. fresh lemon juice

Instructions

Bring sugar and 1 cup water to a boil in a 2-qt. saucepan over high heat; cook, stirring, until sugar is dissolved, 1-2 minutes. Reduce heat to medium-high and add rhubarb; cook until tender, about 5 minutes. Add strawberries and lemon juice; cook 2 minutes more. Strain though a fine-mesh sieve, discarding solids. Pour into a 9" x 13" baking dish, cover with plastic wrap, and place in the freezer. Using the tines of a fork, stir the mixture every 30 minutes, scraping edges and breaking up any ice chunks as the mixture freezes, until granita is slushy and frozen, about 3 hours. Scoop into chilled serving glasses and top with sliced strawberries, if you like.