Preheat the oven to 190°C and set aside.
Halve the aubergines lengthwise. Score the flesh with a sharp knife, making diagonal cuts about 1.5 cm apart from the edge to the center line. Do not cut through the skin. Repeat on the other side so that a crosshatch pattern is created.
Brush both sides of the aubergine halves with oil in a baking dish and season lightly with salt and pepper. Place the aubergine halves cut-side down in the oven for about 30 minutes.
In a large pan, heat the remaining oil and sauté the onion, garlic, sugar, and tomato puree over medium heat. Stir well and heat the tomato sauce through. Season with salt and pepper.
After 30 minutes, remove the aubergines from the oven. Spoon the hot tomato sauce and onion mixture over the aubergines, ensuring they are completely covered. Return to the oven for another 10 minutes.
Remove the baking dish from the oven. Spoon the sauce over the aubergines again, ensuring they are well coated. Let rest for 10 minutes.
Serve the aubergines from the baking dish, spooning the sauce and tomatoes over them. Sprinkle with pine nuts and parsley or mint if desired. Serve with a green salad and/or rice.
