Heat 4 tablespoons of oil in a pan, fry the minced meat in it until crumbly, season with salt and pepper. Wash and clean the tomatoes and cut them into large pieces. Wash and halve the zucchini and remove the seeds with a spoon. Wash and clean spring onion and cut into rings. Mix corn, leek rings and tomato pieces, season with salt and pepper. Spread the minced meat and tomato vegetables on the courgettes.
Season sour cream with salt and pepper. Spread it on the zucchini in a blob. Sprinkle cheese over it and bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for approx. 45 minutes.
Wash the limes, grate dry and grate the peel. Wash coriander, shake dry, pluck leaves from the stalks and chop finely. Crumble nachos, mix with lime zest and koiander. Remove the zucchini from the oven and garnish with the nachos.