In a medium saucepan, combine the blueberries, sugar, salt, lime zest, and lime juice. Cook over medium heat, stirring frequently, until the mixture comes to a boil and the berries pop and soften, about 4 minutes.
1 cup blueberries (fresh or frozen, if frozen, thaw and drain), 1/3 cup granulated sugar, pinch of table salt, zest of one lime, juice of one lime
Pour the berry mixture into a blender and blend until it becomes a mostly smooth puree, about 1 minute. It won’t be completely smooth, and that’s okay. Add the heavy cream and sour cream, then pulse to blend everything together. Taste the mixture and, if you like, add a bit more lime juice or sugar to suit your preference.
3/4 cup heavy cream, 3/4 cup full-fat sour cream