Preparation:

Substitutes
If you can't find bacalao by that name, try whiting or other types of codfish.

You can also use olive oil instead of Aceite con Achiote.

Pre-soak fish
Unless you're using one of the substitutes, bacalao must be soaked to remove the salt content (and sometimes rehydrate). While some recipes call for only eight hours of soaking, I recommend at least 24 hours of soaking the fish (in the refrigerator). If you are watching your salt intake, let it soak for 48 hours, changing the water after the first day.

Prepare fish
Bacalao is typically available with bones or without bones (sin epinas). If you get the boneless, you should slice the fish in the size you want it in your eggs.

If it has bones, put it on a cutting board with the skin down and use a fork to scrape off the meat. This allows the scraping to go around the bones, and the skin below is tough enough to endure the pressure of the fork without tearing.

Put one tablespoon of Aceite con Achiote into a frying pan
Dice one small onion
Add the onion and crushed garlic to the pan
Add the flaked fish to the pan
Stir-fry until the onion is soft
Add two eggs and finish by scrambling them until cooked to your taste.