Into the basic batter mix add the oregano, salt, mustard and whisk together. Then slowly add the beer and water, you must use equal quantities of them, but you may find you won't need it all so just keep adding it until it all comes together and it forms a thick, heavy batter. Allow the batter to rest for a few hours.
Dip the catfish fillets in batter and deep fry in some pre-heated lard, until they are golden and completely sealed, you can use oil if you would prefer. Remove the fish from the lard and allow the fat to drain off, the fish will continue to cook in the middle even after removed.
Put two tortillas side by side and pinch them together so you get the classic taco shape. Place a fillet of fish on each taco and lay some shredded cabbage on top. Then combine the tomatoes, onion and jalapeño together to create a salsa and put some of it on top of the cabbage. Then drizzle over some guacamole and mayonnaise.
Recipe courtesy of Ricky Pina