Peel the fish, fillet, cut into cubes, and place in a bowl. Pour lime juice, cover with foil and refrigerate for 5 hours. Pour boiling water over tomatoes, peel them off and remove seeds. Cut the pulp into cubes. Grind the peppers together with the seeds. Chop the onion.
Place vegetables in a bowl of fish, pour over with olive oil, salt, and pepper. Put in the refrigerator for another 1 hour. Remove the skin from the avocado, cut the pulp into slices, mix with fish and vegetables. Sprinkle with cilantro.