- 1 3/4 cups (230 grams) all-purpose flour
- 1/2 teaspoon granulated sugar
- 1/2 teaspoon coarse or kosher salt
- 1/2 cup (4 ounces or 115 grams), cold unsalted butter, cut into 1-inch pieces
- 1 large egg
- 1 tablespoon water
- 3 large very ripe tomatoes, heirloom or other, sliced crosswise 1/4-inch thick (about 1.5 pounds)
- Coarse or kosher salt
- 1 small garlic clove
- 1 cup (15 grams) basil leaves, loosely packed
- 2 cups (25 grams) parsley leaves, loosely packed
- 2 tablespoons (30 ml) olive oil, plus more for brushing
- 1 tablespoon smooth Dijon mustard (double if it you like mustard; skip if you don’t)
- 2 ounces (55 grams) hard cheese, thinly sliced or coarsely grated (see Note)
- Freshly ground black pepper
For the crust (pâte brisée)
For the filling
Bake shell: Preheat the oven to 375ºF with rack in center. Place the tart pan on a rimmed baking sheet. Weigh the crust down with parchment paper and pie weights, dried beans, or rice (that you don’t plan on using for anything else). Bake crust for 20 minutes. Remove parchment and weights. If there are any cracks or breaks, you can patch with the remaining dough. Bake for 5 minutes more. Remove from oven and let cool.
Make the filling: Meanwhile, place tomato slices on a rimmed baking sheet and lightly sprinkle with salt.
Combine garlic, parsley, basil, and ½ teaspoon salt in a food processor. Pulse until finely chopped. Add olive oil and pulse until a spreadable paste forms. You might need to scrape down the sides of the food processor a few times. If making the herb mixture in advance, store in the refrigerator with plastic wrap pressed against its surface.
Blot tomatoes with paper towels to remove excess liquid.
Using a small spoon or offset spatula, spread Dijon mustard evenly on the bottom of the crust. Evenly distribute cheese on top. Dollop with herb mixture and gently spread to cover in a thin layer. Top with tomatoes, overlapping. Cut smaller pieces of tomatoes to fill gaps. The tomatoes shrink while roasting, so keep them snug and the tart pan full. Lightly brush tomatoes with olive oil and sprinkle with freshly ground pepper.
Bake tart: Until tomatoes are softened and the crust is golden, about 50 minutes and up to 1 hour, until the tomatoes are deeply roasted. Allow to cool slightly then serve warm or at room temperature.
Do ahead: You can make the dough a few days in advance and refrigerate. You can also bake the crust one day and make and bake the filling another, as I did. Leave at room temperature; no need to wrap. Leftovers of the finished tart keep in the fridge for 4 to 5 days.