Recipe from Fiesta at Rick's.
Dislodge the seeds from the pomegranates: One easy way to do this is to cut a generous 1/4 inch off the crown and flower ends of the pomegranates, then score the rind from top to bottom at 1 1/2-inch intervals, cutting about 1/4 inch deep. Fill a large bowl with water. Holding a pomegranate under the water, break it apart into sections, then use your fingers to dislodge the seeds. Get rid of the peel. The white membrane connecting the seeds will float to the top of the water and can be easily scooped off and discarded. The seeds will sink to the bottom. (And in the process, no clothes, walls or countertops will get spattered with the staining crimson of random broken seeds.) Pour the seeds into a colander to drain: you should have 4 cups. Scoop the seeds into a food processor. Pulse to create a coarse puree, releasing the juice but not chopping up the white seeds. (When it’s ready, you’ll see that the white seeds are separate from the pulp.) Press through a medium-mesh strainer to extract as much liquid as possible. Pour the juice into a small saucepan (you should have 1 1/2 cups), set over medium-high heat and boil, stirring frequently, until reduced to 1 cup, about 8 minutes. Cool.
In a large bowl, whisk the sour cream until smooth. Whisk in the cooled pomegranate juice, then all the remaining ingredients.
Freeze in your ice cream machine, according to the manufacturer’s directions. Scrape into a freezer container and freeze for several hours to firm.
The base can be made a day or two ahead. Because the ice cream has no emulsifiers or stabilizers, I recommend serving it within 24 hours of freezing.