Thinly slice the eggplant/aubergines; place them in a colander.
Sprinkle slices lightly with salt; set aside for 1 hour; this drains off any excess water and helps with frying.
Meanwhile, make the simple tomato sauce.
Finely chop 1 onion and sauté in a pan, with the olive oil, until translucent and soft but not browned.
Add the tomatoes and a small bunch of basil which you tear with your hands.
Add a pinch of salt and pepper; stir and simmer gently for 10 to15 minutes; remove from heat; set aside.
Rinse the eggplant slices under cold water and pat them dry with a kitchen towel or paper.
Lightly dust them with flour, shaking off any excess; fry in sunflower oil for a few seconds on each side; drain on paper towels to remove any excess oil.
Pre-heat the oven to 350°F.
Spoon a small amount of tomato sauce into the bottom an 11-inch x 8-inch (or similar size) baking dish and spread it around; this will stop the eggplant from sticking.
Next, add one layer of eggplant to the dish followed by a sprinkling of parmesan cheese, cubes of mozzarella, a sprinkling of pepper and couple spoons of tomato sauce; save ⅓ of the sauce for the final layer.
Continue with the next layer until you have one top layer left.
For the top layer, spoon over the remaining tomato sauce and top with parmesan and mozzarella.
Cover loosely with foil, place in the pre-heated oven and bake for 20 minutes.
Remove from the oven, remove the foil, place back in the oven and bake for another 20 minutes until nice and golden and bubbling on top.
Remove from the oven and let rest for 5 minutes before serving.