How to Make It
Stir together 4 cups water and tapioca in a bowl. Cover and chill 8 hours or overnight.
Drain soaked tapioca, and transfer to a medium saucepan. Add coconut water, and cook over low, stirring often, until heated through, about 5 minutes. Add granulated sugar, coconut milk, coconut extract, and salt, and cook, stirring often, until mixture has thickened and tapioca pearls are tender, about 25 minutes. Transfer to a medium bowl, and cool completely, about 2 hours.
While the coconut tapioca cools, preheat oven to 200°F. Place egg whites in bowl of a heavy-duty stand mixer fitted with the whisk attachment, and beat on medium speed until frothy, about 1 minute. Add cream of tartar and salt, and beat until soft peaks form, 1 to 2 minutes. With mixer running, gradually add superfine sugar, 1 tablespoon at a time, beating until completely incorporated. Increase speed to high, and beat until stiff, glossy peaks form, 2 to 3 minutes.
Using an offset spatula, spread meringue in a 1/4-inch-thick rectangle on a parchment paper–lined baking sheet. Sprinkle with crushed pink peppercorns. Bake in preheated oven until firm and dry to the touch, 2 to 4 hours. Turn oven off, and leave meringue inside oven until completely dry, about 2 hours. Remove from oven, and let cool completely, about 30 minutes. Break meringue into small pieces.
To serve, place 1/4 cup sorbet in each of 8 (8-ounce) serving glasses. Top each with 1/4 cup coconut tapioca, 1 1/2 tablespoons diced mango, 1 1/2 tablespoons diced pineapple, and 1 tablespoon passion fruit pulp. Top each with 1/4 cup sorbet, and garnish with meringue shards and lemon balm. Serve immediately.