- a 3 1/2-to 4-pound piece of watermelon (about a quarter of a large watermelon that has been halved lengthwise and crosswise)
- 1 1/2 ounces fine-quality bittersweet chocolate (not unsweetened), chopped
- 1 cup sugar
- 1/4 cup fresh lime juice
- 2 tablespoons Sambuca or other anise-flavored liqueur if desired
- Cut watermelon into 1-inch-thick semi-circular slices and chop flesh coarse, reserving rind.
- Arrange reserved watermelon rind slices on their sides on foil-lined baking sheets and cover tightly with plastic wrap. Freeze rinds until frozen hard, about 2 hours.
- Line another baking sheet or a tray with parchment or wax paper. In a small bowl set over a small saucepan of barely simmering water melt chocolate and remove from heat. Transfer chocolate to a small resealable bag and seal bag. Snip off tip of one corner of bag to form a tiny hole and onto prepared baking sheet or tray pipe and spread chocolate into 1/3- to 1/2-inch ovals to resemble watermelon seeds. Freeze chocolate “seeds” on baking sheet until very firm, about 30 minutes. Working quickly, peel “seeds” from paper into another small bowl and keep frozen.
- Discard real seeds from watermelon to yield 5 cups. In a saucepan heat 1 cup purée with sugar over moderate heat, stirring, until sugar is dissolved and stir into remaining purée with lime juice and liqueur. Chill mixture, covered, until cold.
- Freeze sorbet in an ice-cream maker. When sorbet is frozen to a thick slush add three fourths of chocolate “seeds” and continue to freeze until frozen.
- Working quickly, fill frozen watermelon rinds with sorbet, smoothing it with a rubber spatula. Arrange remaining chocolate “seeds” realistically on slices and smooth _sorbet_again. Cover sorbet with plastic wrap and freeze until very firm, about 6 hours. (Watermelon sorbet slices may be made 3 days ahead and kept frozen, wrapped tightly).