Mix the flour with the salt, Old Bay® Seasoning, oregano, garlic powder, and pepper. Whisk the beer into the flour mixture until well blended.
Rinse the fish with water and pat dry. Cut the fillets into twelve 1-by-5-inch pieces. Pour soybean oil into a deep skillet to a depth of 3 to 4 inches. Heat to 350°F (or medium-high heat).
Dip fish into batter and coat all sides. Cook several pieces of fish in a single layer in the 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 to drain excess oil.
Heat the corn tortillas in a skillet until soft and hot.
To assemble, first place the tortilla, layer the lettuce on top, followed by the fish, pico de gallo and white sauce. Top with a squeeze of lime.
Mix ingredients until blended. Refrigerate until ready to serve.