For tart dough, stir together flour and salt in a medium bowl. Cube cold unsalted Butter and cut into the flour mixture using a pastry cutter or your clean hands. Mix until the butter is in pea-sized chunks. Then add water by the tablespoon until the dough is shaggy and just barely sticks together.
Scoop dough out onto a clean surface and fold it over itself a few times until it forms a loose ball. If dough is very dry, add more ice water by the tablespoon until it forms a loose ball. Tightly wrap dough in plastic wrap and chill for at least 30 minutes or you can make the dough up to a day in advance.
Preheat oven to 400 degrees F. Slice tomatoes into 1/2-inch slices and place them in a colander. Season with a sprinkle of kosher salt and let drain for 10 minutes.
Remove dough from fridge and roll out into about a 14-inch round. It doesn’t have to be exact. Transfer dough to a baking sheet lined with parchment paper and drizzle dough with olive oil.
Spread ricotta cheese over dough. Leave about two inches of room around the outside so you can fold the dough over. Dot cheese with thinly sliced garlic and top the whole thing with sliced and salted tomatoes. The tomatoes should overlap heavily, but be in a single layer.
Sprinkle tart with salt and pepper and bake for 50 minutes at 400 degrees F. Rotate tart once halfway through to ensure even cooking.
Remove tart and let rest for 10 minutes. Then garnish with fresh chives, slice, and serve.