Clean and wash the lettuce and - if available - spin dry, otherwise pat dry. Peel the avocado and remove the stone, cut into small pieces. Cut open the papaya, remove the black seeds, peel and also cut into small pieces. Peel and finely chop the onion in the same way.
Prepare a vinaigrette from oil, vinegar and spices, add the onions and let it steep. If you like it a little stronger, you can stir in some mustard. The result should be a pleasantly slightly sour sauce.
Add the remaining ingredients, except for the fish, and mix together. Arrange the trout fillets nicely with the salad on plates.
It goes well with baguette or hearty farmer`s bread.