Devein the shrimp. Dice the chillies very finely, seeds can be added. (The heat of the chillies does not come from the seeds, but from the divided inner wall.) Grate the lime peel and then squeeze the lime. Mix the chilli, lime juice, zest and olive oil well with a whisk and season with salt and sugar.
Dice the onions very finely, cut the papaya into small cubes, thinly slice the celery stalks, finely chop the greens and add to the sauce. Likewise the shrimp.
Roughly chop the lettuce into pieces and spin dry or dab well. Lay out the salad on a plate, carefully mix the papaya-shrimp mix and then serve on the prepared salad on plates.