Preheat your oven to 180 degrees Celsius. Place the aubergine slices onto a baking tray. Sprinkle with salt and pepper, as well as the vegetable oil. Rub to ensure the oil is spread throughout the aubergine slices. Roast in the oven until golden brown and soft.

Heat a saucepan and add the olive oil, then the onions. Season with salt and pepper. Sauté until translucent.

Add the tomato paste & cook for 2 min. Add the fresh oregano, chopped tomatoes, and garlic. Stir and bring to a boil, then reduce the heat to simmer. Taste the sauce for seasoning. Simmer for about 10 minutes, then remove from the heat.

In a deep oven-proof dish, layer some aubergines to cover the bottom. Then cover the aubergines with a layer of tomato sauce. Cover the sauce with the grated mozzarella cheese. Then top that with another layer & bake in the oven until golden brown.