Black bean puree: Soak the beans overnight in just under 1/2 l water. Peel and chop the onions. Peel garlic and chop finely. Clean the chilli pepper, carve lengthwise, remove seeds, wash and cut into fine rings.
Wash the thyme, shake dry and pluck.
Pour the beans into a sieve and let them drain. Heat 4 tablespoons of oil in a saucepan. Fry onions, thyme, garlic and chilli in it. Add beans and 150 ml water, bring to the boil, cover and simmer for 1 1/2 - 1 3/4 hours.
Remove the beans from the stove and puree them with a hand blender. Season to taste with salt and pepper.
Guacamole: Peel and chop the garlic. Squeeze the lime. Clean the chilli pepper, carve lengthwise, remove seeds, wash and cut into rings. Wash the coriander and pluck off the leaves. Cut avocados in half, stone them, remove the flesh and dice.
Finely puree the avocados, lime juice, garlic, chilli rings and coriander with a hand blender. Season to taste with salt and pepper.
Tortillas, tacos and everything to fill: Preheat oven (electric cooker: 200°C/circulating air: 175°C/gas: level 3). Dab steaks dry, cut the fat edge several times crosswise. Heat 2 tablespoons of oil in a pan.
Fry the steaks for 3-4 minutes on each side. Season with salt and pepper and remove. Wrap in aluminium foil and let it rest for about 10 minutes. Then cut off the fat edge and cut the steaks into fine strips.
Grate cheese. Clean and wash the salad and cut into fine strips. Wash and chop the tomatoes. Put the tortilla flat cakes next to each other on a baking tray. In a hot oven
Fill tortillas and tacos at the table to taste with steak strips, lettuce, tomatoes, guacamole, bean purée, cheese and sour cream.