Bruschetta With Eggplant Relish & Ricotta Salata Cheese

Yields 8 portions 3 lb eggplant, peeled, cut into 1/2-in cubes 2 teaspoons kosher salt, plus as needed 3/4 cups minced onions 1/4 cup plus 2 tablespoons extra-virgin olive oil, divided use 1/2 cup (2 stalks) small-dice celery 1 1/2 cups tomato purée 1/2 cup pitted green olives, diced 1/4 cup capers, rinsed…