Remove skin and bones from fish and flake the flesh with a fork.
In a deep bowl, mash the egg yolks with the milk until they form a smooth paste. Add sugar, salt, and 1 table-spoon of the lime juice. Then beat in the vegetable oil, a teaspoon or so at a time. Add the olive oil in the same gradual manner. Chop egg whites finely and add them to the bowl, along with the fish. Combine thoroughly but gently.
Just before serving, cut the avocados in half, remove pits, and fill cavities with the fish mixture. Garnish with pepper or pimento, and pass around the remaining lime juice to sprinkle on individual servings.
(picure : google image)