2 ounces dark chocolate, chopped
1⁄8 teaspoon peppermint extract
2 1⁄2 pounds (with rind) seedless watermelon
1⁄2 cup sugar
6 tablespoons Lillet Blanc
1 pinch kosher salt
1. Melt: Tumble chocolate into a microwave-safe bowl and zap on low power until just melted, about 1 minute. Drop in peppermint and work smooth with a soft spatula. Scrape into a small zip-top bag.
2. Shape: Line a baking sheet with parchment paper. Snip a corner off the bag and squeeze drops of melted chocolate onto the paper, forming 60 or so seed shapes. Slide sheet into the freezer and let set, 5 minutes.
3. Slice: Cut each lime in half across its equator. Run a grapefruit knife around the interior rim, separating flesh from rind. Lift out flesh, leaving 12 lime shells.
4. Pulse: Scoop out watermelon flesh. Use the food processor to pulse to bits, along with flesh of one lime. (Save remaining lime middles for another project.) Press purée through a medium-mesh sieve into a quart-sized measuring cup. There should be about 2 cups juice. Stir in sugar, wine, and salt.
5. Swirl: Churn in an ice-cream maker. Slide most of the chocolate seeds into the melon ice on the last turn.
6. Freeze: Scoop ice into the lime shells. Sprinkle remaining chocolate seeds on top. Set filled limes on an empty ice-cube tray or into a muffin tin to pre- vent tipping. Cover with plastic wrap and freeze until firm, about 2 hours. Scoop up with a spoon inside or slurp Popsicle-style outside.