For the green sauce, cut the onion into fine cubes, wash it with cold water to lower its intensity and mix with the cilantro, lemon juice, salt, pepper and olive oil.
For the shallot vinaigrette, put the sherry vinegar, shallots and olive oil in a blender, blend everything and add salt and pepper.
Horseradish paste, passion fruit and caviar can be found at any supermarket.
When serving, put crushed ice on a plate, and the 5 oysters over it. Add one dressing -green sauce, shallot vinaigrette, caviar, horseradish and passion fruit- on top of each oyster and serve.