Peel oranges so that the white skin is completely removed. Cut oranges into thin slices. Clean, wash and slice the fennel. Halve avocado, remove core, peel off flesh and cut avocado into thin slices.
Wash mint, shake dry and pluck leaves. Clean the chilli, cut lengthwise, wash and remove seeds. Cut the pod into small pieces.
For the vinaigrette, mix vinegar with salt, pepper and sugar. Fold in 2 tablespoons of olive oil drop by drop. Arrange orange, fennel and avocado slices alternately on a plate. Drizzle the vinaigrette over them.
Mix the crab meat, mint, chilli and 2 tablespoons of oil. Season to taste with salt and pepper. Arrange in the middle of the plate. Sprinkle with pepper.