Core and cut half of the honeydew melon. Cut two eighth strips along the skin and cut the remaining pulp into small pieces. Squeeze the lemon. Halve, stone and peel the avocado. Rub with lemon juice. Cut half of it into thin slices and dice the rest. Cut the radishes into slices and the basil leaves. Halve a trout fillet 1, cut the rest into small pieces.
Place one melon strip with the skin on a plate vertically and put the avocado strips in between. Place half a trout fillet next to it.
Mix the rest and season with lemon juice, salt, coarsely ground pepper and cayenne pepper.