For the vinaigrette, wash organic lime hot, rub dry and finely grate the skin. Squeeze all the limes. Mix the lime zest, juice and oil. Season with salt and pepper.
Cut the melon into slices. First cut the flesh from the skin, then dice. Cut avocados in half and remove seeds. Remove the flesh from the skin and dice. Mix melon and avocado with the vinaigrette and chill for about 1 hour. Season to taste with salt and pepper.
Wash the shrimps and pat them dry well. Grill in a lightly oiled grill tray in portions on each side for 1-2 minutes. Season with salt and pepper. Arrange the prawns on the salad.