Pescado Ceviche - cooking recipe

Ingredients

1 lb fresh tuna (cod, orange roughy, and red snapper are other good choices. You can also mix-and-match different typ) or 1 lb other firm-fleshed white fish (cod, orange roughy, and red snapper are other good choices. You can also mix-and-match different typ)
3 lemons, juice of
3 limes, juice of
1 garlic clove, minced
1 small red onion, minced (about 1 cup)
1 jalapeno, chopped fine
2 tablespoons finely chopped cilantro
2 tablespoons parsley
2 small firm-fleshed tomatoes, chopped finely
salt
1 avocado, sliced (optional)

Preparation

Soak the fish in salted water for 10 minutes, gently pat dry with a paper towel. Cube the fish, and place in a shallow dish.
Arrange the onions on top of the fish, and cover with the remaining ingredients. Allow to refrigerate at least 4 hours. Be sure to stir several times. The fish is done once the flesh turns white and opaque, and can be flaked slightly with a fork. This indicates that the acidity of the citrus has denatured the proteins in the fish- the same thing that happens when we \"cook\" in the traditional sense.
Serve chilled, garnished with avocado, if desired.