I had to post this recipe because it is so easy to make and so good. I adapted it from an Epicurious recipe, but the secret ingredient is something I learned about on here: Lime oil.
1 3/4 cup sugar
1/2 cup lime juice
zest from one lime
4 cups buttermilk
splash of limoncello
about 1/2 tsp lime oil
Stir it together, let it refrigerate for a while to cool and marry the flavors, then run it through your ice cream maker.
It's refreshing, tart, just sweet enough, and has a lingering lime flavor thanks to the lime oil.