How to Make It
In a small saucepan, whisk together the sugar, salt, lemon zest, and egg yolk until smooth. Add the pineapple juice and butter and stir until smooth. Bring to a simmer over medium heat, stirring constantly. Once it begins to simmer, continue to cook and stir the curd until it is thickened and coats the back of a spoon, about 2 minutes. Transfer to a bowl and let cool to room temperature. Cover with plastic wrap and refrigerate until ready to use.
Heat the oven to 350°. In a small bowl, stir together the cornstarch, vinegar, vanilla, and salt until a thick paste forms. Put the sugar and egg whites in the bowl of a stand mixer fitted with the whisk attachment and mix on low speed until smooth. Increase the speed to medium-high and beat until soft peaks form. Add the cornstarch paste to the beating egg whites and continue to beat until very stiff and glossy peaks form, about 5 minutes. Add the pistachios and, using a rubber spatula, very gently fold until evenly incorporated.
Trace a 9-inch circle onto a sheet of parchment paper. Flip the sheet over and transfer it to a baking sheet; spray lightly with baking spray. Pile the meringue in the center of the circle and, using an offset spatula or small rubber spatula, form it into a 9-inch disk, smoothing the top and sides. Transfer to the oven and immediately lower the oven temperature to 215°. Bake until the meringue is dried on the outside and looks set, about 1 1/2 hours. Without opening the door, turn the oven off and let the meringue sit inside until completely cooled, at least 4 hours. (The cooling process allows the meringue to dry and cool slowly enough so that it doesn’t collapse on itself.) Once cooled, gently tip the meringue onto its side and peel away the parchment paper. Carefully place the meringue on a flat cake stand or serving platter.
In a food processor, combine the sugar, orange zest, salt, and coconut milk in a food processor and process until the sugar is dissolved and the zest heavily perfumes the coconut milk. Pour into a large bowl, add the cream, and whisk until stiff peaks form. Pile the whipped cream onto the center of the meringue and gently nudge it to the edge of the meringue, leaving about a 1 1/2-inch border.
Arrange the orange and grapefruit segments on the cream and then drizzle with some of the pineapple curd. Dot the top with cherries, coconut, lime zest, and more chopped pistachios and serve immediately.