This is just a rough recipe - basically like spicy salsa with fish added. If using rock cod, freeze your fish first to make sure any parasites are killed off. Fresh halibut is awesome with this.
(3-4) Tomatoes
(4) Limes
(2) Garlic Cloves or to taste
(1) Bunch Cilantro - use to taste
(1) White Onion - use to taste - usually about 1/2 the onion
(1) Tbsp Spicy Chili Garlic Sauce (look in the asian foods section)
8-12 oz of fish fillets
Take the fish fillets and cut into small pieces, i.e salsa bite size chunks. Squeeze the juice from 3 limes and put into a ziplock bag then add your fish. Mix the lime juice around the fish and let it sit for 45 minutes or so stirring around occasionally.
While the lime juice "cooks" the fish, chop the tomatoes, onion, garlic and cilantro. Mix in a bowl. Squeeze the juice from the last lime over the tomatoes etc. Mix well.
Now add the Chili Garlic Sauce a little bit at a time - season to taste - this stuff has a kick.
Lastly add the fish and mix it in. Great with tortilla chips, wrapped in tortillas, pita chips etc.