For the sauce, peel and dice the garlic. Heat 1 tablespoon of oil. Fry garlic, chilli and oregano briefly. Sweat tomato paste with. Stir in tomatoes, 400 ml water and stock. Season with salt, pepper and 1 pinch of sugar and simmer open for about 10 minutes.
Rinse corn and beans in a sieve and drain well. Heat 2 tablespoons of oil in a large frying pan. Fry the minced meat until crumbly. Season with salt and pepper. Add sauce, except 200 ml, corn and beans to the mince. Season minced meat mass and the rest of the sauce to taste. Grate cheese.
Line a casserole dish (approx. 4 l capacity) overlapping with 4 tortillas. Spread approx. 1⁄3 chopped mass and approx. 1⁄4 cheese on top. Cover with 4 tortillas. Repeat the process twice, finish with tortillas. Spread the rest of the sauce and cheese on top. Cover with foil and bake in a hot oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer) for about 20 minutes. Bake open for another 20 minutes.
For the topping, cut the avocado in half, remove the seeds, remove the flesh from the skin and dice. Wash the coriander and remove the leaves. Mix both with juice. Serve lasagne with it.