Peel oranges and remove the inner membrane and the seeds from each slice. Then cut the slices to bite, put in a bowl and stir in the coriander. Sprinkle with a little olive oil and with 1 pinch of pepper.
Peel avocados and cut in thin slices or cubes. Pour the juice of lemons, salt and add the onion, 1 pinch pepper and 3 tablespoons olive oil. Keep them covered.
Peel prawns, leaving the tails in place. Place the orange juice, sugar, vinegar and balsamic vinegar with 1 tablespoon olive oil in a large frying pan and add 1 pinch of pepper. Leave the mixture to boil over low heat until it thickens into a liquid caramel. Deep in the shrimps, turn to catch the caramel everywhere and cook for 2-3 minutes, until it changes color and curl.
Lay on a platter or individual plates avocados, put the oranges on top and the hot shrimp. Serve immediately.