For the soup, clean the chilli, carve lengthwise, remove seeds and chop coarsely. Peel and chop the onions and garlic. Heat 1 tablespoon of oil in a large saucepan. Sauté onions and garlic in it. Add the polenta and stir-fry for 3-4 minutes.
Add the tomatoes and juice, 1 1/2 l water, 1 tablespoon sugar, oregano and chilli. Bring to the boil, stir in the stock and simmer everything for about 15 minutes, mashing the tomatoes.
For the side dishes, cut tortilla flat cakes into fine strips of approx. 3 cm. Heat 1/4 l oil in a pan with a high rim. Fry the tortilla strips in it in 3 portions until golden brown. Lift them out and let them drip off on kitchen paper.
Halve the avocado and remove the stone. Remove the flesh from the skin and dice finely. Sprinkle with lime juice. Crumble cheese and stir sour cream until smooth. Fill all side dishes into bowls.
Puree the soup with a hand blender. Season to taste with salt, pepper and sugar. Wash the coriander, shake dry and sprinkle over the soup. Serve the soup as desired with the side dishes.