Wash the cucumber, peel it, cut it in half lengthwise and remove the seeds with a tablespoon. For the vinaigrette, dice 1/2 cucumber. Pour into a tall mixing bowl. Clean and wash the chilli pepper, cut lengthwise, remove seeds and cut into fine strips. Halve the orange and squeeze the juice. Peel ginger and grate finely
Add orange juice, ginger, sugar and fish sauce to the cucumber. Puree everything finely with a blender. Add the chilli. Season to taste with salt and pepper
Clean the salad, wash and shake dry. Put four leaves aside. Chop remaining salad leaves. Chop the remaining half cucumber. Cut avocado in half, remove core, peel. Cut off 8 slices, sprinkle with lime juice and put aside. Chop remaining avocado
Wash the coriander, shake dry and pluck the leaves from the stems. Pour the crayfish into a sieve and drain. Mix the coriander, except for a few leaves for garnishing, chopped avocado, cucumber and chopped lettuce with the cucumber vinaigrette
Arrange lettuce leaves and avocado slices on 4 plates. Arrange the salad on top, place the crayfish on top and garnish with the remaining coriander.