4 cups, ½ inch cubed, seedless, watermelon
½ cup sugar
2 tablespoons lime juice

Purée all ingredients in a blender. Pour into a 9- by 13-inch dish and place in the freezer. Scrape with a fork every 30 minutes until mixture forms ice flakes (up to 2 1/2 hours).

This can be made 3 days ahead of time but it must be scraped at the correct intervals. If you place it in the freezer and forget to do the scraping, it will form a strong block of ice and will be impossible to work with. Each time you take it out, scrape it until the entire tray is full of flaked ice. If you it is too tough, microwave it a bit, and start over with the freezing and scraping.