Grapefruit-Orange Crostatas

Preparation

1. Dough:

   Step 1

   Beat butter, flour, sugar, and salt in the bowl of a stand mixer fitted with the paddle attachment on low speed until butter is in flat pieces the size of a nickel or smaller (mixture should look slightly sandy). Combine vinegar and 1/4 cup ice water in a small bowl and, with motor on low speed, stream into mixture. Beat, adding another 1–2 tsp. ice water if needed, until no dry spots remain. Continue to beat until dough begins to clump together, but stop before it starts to form a ball.

   Step 2

   Transfer dough to a surface; squeeze and flatten a couple times to bring together. Divide into 4 pieces. Flatten into 1/2"-thick disks; wrap tightly in plastic. Chill at least 1 hour and up to 2 days.

2. Frangipane and assembly:

   Step 3

   Place a rack in middle of oven and preheat to 400°F. Whisk semolina flour, salt, 5 Tbsp. sugar, and 1 Tbsp. plus 1½ tsp. all-purpose flour in a medium bowl. Finely grate zest from grapefruit and orange into another medium bowl; set fruit aside. Add vanilla paste and 4 Tbsp. room-temperature butter to bowl with zest and mix until smooth. Add egg and egg yolk and mix vigorously to combine. Add dry ingredients; mix just until incorporated.

   Step 4

   Cut remaining peel and pith away from reserved citrus; discard. Slice fruit into 1/2"-thick rounds; wriggle out seeds.

   Step 5

   Working one at a time, roll out dough disks on a lightly floured surface to 8" rounds. Place on a parchment-lined baking sheet and spread 1/4 cup frangipane in the center of each, leaving a 1 1/2" border. Arrange citrus rounds over frangipane to cover, then fold edges of dough up and over fruit. Chill 30 minutes.

   Step 6

   Brush fruit and crust with melted butter and sprinkle with remaining 2 Tbsp. sugar (avoid getting it on the baking sheet). Bake crostatas, rotating once, until crusts are golden brown with a few darker spots, 40–45 minutes. Let cool at least 10 minutes before serving.