To make the tart dough, in the bowl of a food processor, combine the flour and salt and pulse 2 or 3 times to combine.
Add the butter and pulse until the mixture resembles coarse meal.
Add the 1/4 cup (2 fl. oz./60 ml) ice water and pulse 3 or 4 times. The dough should hold together when squeezed with your fingers but should not be sticky. If it is crumbly, add more water, 1 tsp. at a time, pulsing twice after each addition.
Turn the dough out onto a work surface and shape into a 5-inch (18-cm) disk. Wrap with plastic wrap and refrigerate for at least 1 hour or up to overnight.
Preheat oven to 400°F (200°C).
On a lightly floured surface, roll out the dough to 1/8 inch (3 mm) thick to fit a 10 1/4-inch (26-cm) round tart pan.
Press the dough into the pan and trim, leaving a 1/2-inch (12-mm) overhang around the rim.
Fold in the excess dough and press it into the sides so they are thicker than the bottom. Refrigerate at least 10 minutes.
Place the tart pan on a baking sheet. Place a sheet of parchment on top of the dough and fill the pan with pie weights.
Bake for 12 minutes, then remove the parchment and weights and continue baking until the crust is baked through and light golden brown, about 10 minutes.
Transfer to a wire rack and let cool completely in the tart pan.
In a bowl, combine the ricotta, Parmesan and basil and season to taste with salt and pepper. Using a small spatula, spread the mixture into the cooled tart shell. Top with the tomato slices and sprinkle with sea salt and basil leaves. Serve immediately.