Clean and wash the aubergines and cut them into slices about 1 cm thick. Sprinkle a baking tray with 1 tsp. salt. Spread the slices on top and sprinkle with about 1 teaspoon of salt. Let the aubergines steep for about 1 hour.
Dab aubergines dry. Dab the tray dry and brush with 1 tablespoon of oil. Spread the aubergines on top and brush with 2 tbsp. oil. Fry the aubergine slices under the hot oven grill for approx. 15 minutes, turning once.
For the sauce, peel and finely dice the onions. Heat 1 tablespoon of oil in a frying pan. Fry the minced meat in it until finely crumbly, fry the onions briefly. Stir in tomato paste and 150 ml water, bring to the boil. Season with salt, cayenne pepper and 1 tsp. coriander.
Preheat oven (electric cooker: 200 °C/circulating air: 180 °C/gas: see manufacturer). Wash, clean and slice the tomatoes. Put half of the sauce in an ovenproof dish. Layer aubergines and tomatoes. Season with salt and pepper. Spread the rest of the sauce over the tomatoes. Close the tin with aluminium foil and bake in a hot oven for about 15 minutes.
Peel and chop the garlic. Wash mint, shake dry, pluck off leaves and cut into strips. Mix both with yoghurt. Season with salt and pepper. Spread some yoghurt on the casserole, add the rest.