1 (15- to 20-oz) can lychees in syrup
1/2 cup well-stirred sweetened cream of coconut (preferably Coco L?ez brand; not coconut milk or coconut cream)
3 to 3 1/2 tablespoons fresh lime juice
1 firm-ripe large mango (1 lb), peeled and sliced
1 teaspoon finely grated fresh lime zest
Special equipment: an ice cream maker

Drain lychees, reserving syrup, then pur? lychees, cream of coconut, 1/4 cup syrup, and 2 1/2 tablespoons lime juice in a blender until smooth. Freeze in ice cream maker.
While sorbet is churning, toss together mango, zest, and remaining lime juice to taste (1/2 to 1 tablespoon).

Serve scoops of sorbet over mango slices.