This recipe from Eating Well was created rather quickly after I found it, simply because it's summer. Watermelon is reasonably priced at the grocery store, and my kids love watermelon. I thought this would be a win for them, but it turns out that neither of them loves it.
Dave and I find it refreshing. It's authentic watermelon flavor that's not cloying but just sweet enough to taste relatively healthy. It definitely needs to stand at room temperature at least 5-10 minutes before scooping because it, like custard, is best not fully frozen.
6 1/2 cups seedless watermelon, cubed
14 oz. sweetened condensed milk
1/2 cup lime juice
1/4 tsp. salt
Place watermelon on large baking sheet, and freeze until frozen. Puree frozen watermelon with the remaining ingredients, breaking into smaller batches if needed, until smooth. Transfer to a large container with a cover, and freeze until firm. Makes about 6 cups of sherbet.