Sauté the onion, garlic and ginger (if using) in the olive oil. Add the tomatoes and a little water. Tie the herbs up into a bunch and add with the bay leaves and the sugar. Simmer the sugo for approx. 40 mins., season. Remove the herbs and bay leaves, set the sugo aside.
Place the aubergines on a baking tray lined with baking paper, season with salt and leave to stand for approx. 15 mins. Dab off the excess liquid with kitchen paper. Brush the aubergines with olive oil.
Bake for approx. 20 mins. in the centre of an oven preheated to 200 °C (the aubergines must be soft). Put to one side and let cool.
Involtini di melanzane
Spread 1/4 of the sugo over the base of the ovenproof dish. Individually brush the aubergine slices with sugo, top each with a piece of mozzarella and a basil leaf, shape into rolls and place them in the dish, on the sugo. If there is any mozzarella left over, scatter over the rolls. Spoon the rest of the sugo on top and sprinkle with the parmesan.
Bake for approx. 30 mins. in the centre of an oven preheated to 180°C.