01 - Blend flour, powdered sugar, and salt in a food processor. Add cold butter and pulse until mixture resembles coarse crumbs. Add egg yolk and 1 tablespoon cold water, pulsing until dough just comes together. Add remaining water if dough is too dry. Flatten into a disk, wrap in plastic, and refrigerate for 1 hour.
02 - Roll dough on lightly floured surface to fit a 9-inch tart pan. Press dough into pan, trim edges, and prick base with fork. Refrigerate shell for 15 minutes. Preheat oven to 350°F. Line shell with parchment paper and fill with baking weights. Bake for 15 minutes, remove weights and paper, then bake 10 additional minutes until golden. Cool completely.
03 - Whisk mango puree, eggs, egg yolks, sugar, and lime juice in saucepan. Cook over medium-low heat, stirring constantly, for 10 minutes until thickened enough to coat back of spoon. Remove from heat. Stir in butter cubes until melted and smooth. Strain through fine mesh sieve for silky texture.
04 - Pour mango curd into cooled tart shell, smoothing top with spatula. Refrigerate for at least 1.5 hours until completely set.
05 - Arrange fresh mango slices, toasted coconut flakes, and mint leaves on top just before serving. Serve chilled.