Cut eggplant in slices of salt and leave for 1 hour. Then fry in vegetable oil on both sides.
Finely chop the onions and tomatoes without the skins and fry them in the same way.
Put the eggplants in a pan with the tomatoes. Pour in water and add vinegar, sugar, salt and pepper to taste. Stew for 20 minutes.
Cool and serve completely.