serves 5
3/4 cup sugar
3/4cup water
1/8 teaspoon kosher salt
1 1/4 cups fresh watermelon juice
2 teaspoons lime zest
1/4 cup fresh lime juice
Garnish watermelon wedges, lime slices
In a small heavy-bottomed saucepan, combine sugar, ½ cup water, and salt. Cook over low heat, stirring constantly, until sugar dissolves. Add watermelon juice and lime zest and juice, stirring until well combined. Transfer mixture to a freezer-safe medium shallow dish. Cover and freeze until edges of mixture begin to set, 30 minutes to 1 hour.
Using a fork, scrape mixture to break up frozen pieces. Freeze until mixture resembles fluffy shaved ice, about 4 hours, scraping with a fork to break up frozen pieces every 30 minutes. Serve in chilled glasses. Garnish with watermelon wedges and lime slices, if desired.