Dice the eggplants, cover them in salt for about an hour, and then rinse them with fresh water. After draining or patting them dry, fry them. Do not cook them all the way through; lightly fry them until golden. Meanwhile, wash the celery, remove the leaves, and chop the stalks into small pieces (about one centimeter). Boil the celery until it softens. Next, sauté a generous amount of finely chopped onion, then add the tomato sauce, olives, and the boiled celery. Finally, add the eggplants and continue to cook, ensuring the sauce at least partially covers them. Once fully cooked, it is time to make the sweet-and-sour finish. Nothing could be simpler: add the vinegar to the prepared eggplants, immediately followed by the sugar. Let everything simmer over moderate heat for a few minutes. It is best to let it rest for a few hours. Once the caponata has cooled down, garnish it with the reserved celery leaves, fresh basil, and capers.