Celery, carrots and onion peel, dice finely. Peel garlic and chop finely. Heat the oil in a large, deep frying pan. Stir-fry the chopped garlic for 8-10 minutes. Season with salt and pepper. Add the diced vegetables and fry for about 2 minutes. Stir in tomato paste. Deglaze with red wine and tomatoes. Season with salt, sugar and pepper. Let simmer for about 30 minutes at medium heat, stirring occasionally
In the meantime, peel and wash the potatoes and cut them lengthwise into thin slices of about 3 mm. Wash basil, shake dry and cut into fine strips. Stir the basil into the sauce except for a little to garnish. Season to taste with salt and pepper
Grease an ovenproof dish (approx. 18 x 26 cm). Line the bottom of the dish with 1/3 of the potato slices. Spread half of the Bolognese on top. Alternately layer potatoes and sauce. Finish with potatoes. Drain mozzarella and pluck into pieces. Sprinkle over the casserole. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for 50-60 minutes. If necessary, cover with aluminium foil after approx. 40 minutes. Sprinkle potato and bolognese casserole with the remaining basil