Pour beans and corn into a sieve and rinse. Clean and wash spring onions and cut into rings. Peel and chop the onion. Wash and halve the tomatoes. Wash, clean and seed the chilli and cut into fine rings
Heat the oil in a pan and braise the prepared vegetables, except for the green of the spring onions, for about 10 minutes while turning. Season to taste with salt, cumin and chilli powder. Fold in the green of the spring onions. Coarsely grate cheese
Place the vegetables in the taco shells and sprinkle with cheese. Arrange taco shells and sour cream