📖 Instructions

1. Prepare the Pastry Dough: In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, and salt. Make sure it's all well combined. Next, add the cold, cubed unsalted butter. Using a pastry blender, two knives, or your fingertips, cut the butter into the flour mixture until it resembles coarse meal with some pea-sized pieces of butter still visible. This is crucial for flakiness, so don't overmix it.
2. Add Ice Water: Gradually add the ice water, one tablespoon at a time, mixing lightly with a fork until the dough just starts to come together. Be careful not to add too much water; you want it to be just moist enough to form a ball. If it feels too dry, add another half-tablespoon of water. The key is minimal handling.
3. Form and Chill: Turn the dough out onto a lightly floured surface. Gently gather it into a flat disc. Wrap the disc tightly in plastic wrap and refrigerate for at least 30 minutes, or up to 2 days. This chilling time is super important for relaxing the gluten and making the dough easier to roll.
4. Preheat Oven and Prepare Pan: While the dough chills, preheat your oven to 400°F (200°C). Lightly grease a 9-inch tart pan with a removable bottom. You can also place it on a baking sheet to catch any potential drips, which happens sometimes with juicy fruit. It’s a good safety measure.
5. Roll Out the Dough: On a lightly floured surface, roll out the chilled dough into a 12-inch circle, about 1/8-inch thick. Try to work quickly to keep the butter cold. Gently transfer the dough to your prepared tart pan. Press it carefully into the bottom and up the sides. Trim any excess dough from the edges, leaving a small overhang. You can crimp the edges if you like for a pretty decorative touch.
6. Blind Bake the Crust (Optional but Recommended): Prick the bottom of the crust all over with a fork. Line the crust with parchment paper and fill with pie weights or dried beans. Bake for 15 minutes. Remove the weights and parchment, then bake for another 5-7 minutes, or until the crust is lightly golden. This helps prevent a soggy bottom. Remove from oven and reduce oven temperature to 375°F (190°C).
7. Prepare the Filling: In a large bowl, combine the sliced strawberries and chopped rhubarb. Sprinkle with granulated sugar, cornstarch, lemon zest, and vanilla extract. Toss gently until the fruit is evenly coated. The cornstarch is our secret weapon against a watery filling, it helps thicken all those delicious fruit juices.
8. Assemble the Tart: Pour the fruit filling into the partially baked tart crust, spreading it evenly. You want to mound it slightly in the center.
9. Create a Lattice Top (Optional): If you have leftover dough (from trimming or if you made extra), you can roll it out and cut it into strips to create a beautiful lattice top. Arrange the strips over the fruit filling in a woven pattern.
10. Egg Wash and Sugar: In a small bowl, whisk together the egg yolk and 1 tablespoon of water to create an egg wash. Lightly brush the edges of the crust (and any lattice strips) with the egg wash. Sprinkle a little extra granulated sugar over the crust for a beautiful, sparkling finish.
11. Bake the Tart: Place the tart on the baking sheet (if not already there) and bake in the preheated 375°F (190°C) oven for 45-55 minutes. The tart is done when the crust is golden brown and the fruit filling is bubbly and tender. If the crust starts to brown too quickly, you can loosely tent it with aluminum foil.
12. Cool and Serve: Once baked, carefully remove the tart from the oven and let it cool on a wire rack for at least 30-60 minutes before serving. This cooling time allows the filling to set properly, ensuring clean slices. Trust me, it’s hard to wait, but it's worth it! Enjoy warm or at room temperature.