1. Mix the flour with the salt, Old Bay seasoning, oregano, garlic powder, salt and pepper. Whisk the beer into the flour mixture until well blended.
2. Rinse the fish with water and pat dry. Cut the fillets into twelve 1-by-5-inch pieces. Pour canola oil into a deep skillet to a depth of 3 to 4 inches. Heat to 350° F.
3. Dip fish into batter and coat all sides. Place several pieces of fish in a single layer in hot oil. Cook for about 4 minutes or until the batter is crispy and golden brown. Repeat with the remaining fish. Lay them on a plate covered in a paper towel.
4. Heat the corn tortillas in a skillet until soft and hot.
5. To assemble, layer the lettuce, place the fish on top, add salsa (pico de gallo) and the white sauce. Top with a squeeze of lime. Fold tortilla over to serve.