Grapefruit Curd

1. In a medium pot, whisk together sugar, cornstarch, and salt. Slowly add grapefruit juice while whisking until combined, then whisk in egg yolks.

2. Place the pot over medium heat and cook, whisking constantly, until the mixture thickens and big bubbles begin to break the surface (5-8 minutes). Remove from heat and whisk in butter, one piece at a time. Add food coloring (if using) until desired color is reached. Transfer to a medium bowl and let cool to room temperature. Cover with plastic wrap, pressing it directly against the surface of the curd, and refrigerate until ready to use.

3. Make Ahead: Curd can be made up to 3 days ahead. Keep refrigerated.

Crust

1. In a food processor, pulse almonds until finely ground. Add flour, sugar, and salt, and pulse to combine. Add butter and pulse until a dough begins to form (when pressed between your fingers, the dough should stick together).

2. Transfer the dough to a 9″ tart pan. Using your hands, press the dough into the sides and bottom of the pan. Using a fork, poke holes all over the bottom of the dough. Freeze until firm, at least 30 minutes and up to overnight.

3. Preheat the oven to 350°F (175°C). Place the tart pan on a baking sheet.

4. Bake the crust until golden all over, 12 to 15 minutes.

5. Pour the curd over the top of the crust and smooth into an even layer. Press plastic wrap directly against the surface of the curd and refrigerate until cold, at least 2 hours and up to overnight.

6. Make Ahead: Crust can be made 2 days ahead. Keep covered and store at room temperature.

Meringue

1. In a food processor, pulse sugar, strawberries, and grapefruit zest into a fine powder.

2. Fill a medium pot with about 3″ of water. Bring to a simmer over medium heat.

3. In a medium heatproof bowl, whisk together strawberry powder, egg whites, and cream of tartar. Place the bowl over the simmering water, ensuring the bottom of the bowl does not touch the water. Cook, whisking frequently, until the mixture reaches 160°F on an instant-read thermometer (about 3-4 minutes).

4. Remove the bowl from heat. Using a handheld mixer on medium-high speed (or transfer the mixture to a stand mixer fitted with the whisk attachment), beat until the mixture is glossy, triples in size, and stiff peaks form (about 3-4 minutes).

5. Remove plastic wrap from the top of the tart. Spoon meringue on top, covering completely or just around the border. Use the back of a spoon to create swoops, if desired.

6. Tip: It’s best to serve the tart immediately after topping, but it can be refrigerated fully assembled for up to 1 hour.