Peel onion, cut 1 half into rings. Chop the remaining half finely. Clean, wash and slice the chilli pepper and scrape out the seeds. Chop the pod finely. Knead onion, chili and minced meat, season with salt and pepper. Heat oil in a small pan. Shape the minced meat into a flat meatball, fry in the pan on both sides for 5-6 minutes each
Wash and clean the tomato. Finely dice 1/2 tomato, season in a bowl with salt and pepper. Cut the other half into slices. Remove the avocado flesh from the skin and cut diagonally into longish slices. Wash the salad and drain
Cover the bottom half of the roll with lettuce and tomato slices, add mayonnaise. Arrange the meatball, cheese, onion rings, diced tomatoes and avocado slices on top. Cover with the upper half of the roll and arrange on a plate with halved cherry tomatoes