Onions peel and roughly chop. Wash, clean and chop the tomatoes. Wash the meat, dab dry and rub all around with Cajun spice and salt. Roll up the meat and tie up with kitchen string
Heat the oil in a frying pan. Sauté the rolled roast vigorously while turning. Add onions and fry. Add tomatoes and fry briefly. Season with salt and pepper. Deglaze with stock and bring to the boil. Cover and braise in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 2 hours.
Drain the jalapeños. Wash and clean the salad and drain as well. Coarsely grate the cheese. Remove the roast from the roaster, season the roast stock with salt and pepper if necessary. Cut the meat into slices and pluck. Heat the tortilla flat cake according to the instructions on the packet and then cut into quarters
Serve the meat, jalapeños, lettuce, cheese, crème fraîche and stewed stock together with the onions and tomatoes separately in small bowls. Top the tortilla flat cakes with it as desired. Sprinkle with Cajun spice