Step 1: Prepare the zesty slaw. In a medium bowl, combine the shredded green and red cabbage, chopped fresh cilantro, and thinly sliced red onion. In a small separate bowl, whisk together 2 tablespoons of fresh lime juice, 1 tablespoon of olive oil, a pinch of salt, and a dash of black pepper. Pour the dressing over the cabbage mixture and toss well to combine. Cover and refrigerate while you prepare the rest of your fish tacos recipe.
Step 2: Next, prepare the creamy taco sauce. In another small bowl, combine the Mexican crema, mayonnaise, 1 tablespoon of fresh lime juice, minced garlic, hot sauce, ground cumin, and a pinch of salt. Whisk until smooth and well combined. Taste and adjust seasonings as needed. Cover and refrigerate.
Step 3: Prepare the fish. Pat the cod fillets very dry with paper towels. In a shallow dish, combine the all-purpose flour, cornstarch, smoked paprika, chili powder, garlic powder, onion powder, 1/2 teaspoon of salt, and 1/4 teaspoon of black pepper. Whisk to combine evenly. Dredge each fish fillet in the flour mixture, ensuring it's fully coated. Gently shake off any excess flour.
Step 4: Heat the oil. In a large skillet or cast-iron pan, heat 3-4 tablespoons of vegetable oil over medium-high heat until shimmering.
Step 5: Cook the fish. Carefully place the flour-coated fish fillets into the hot oil, being careful not to overcrowd the pan (cook in batches if necessary). Cook for 3-4 minutes per side, until golden brown and cooked through, and the fish flakes easily with a fork. Adjust heat if necessary to prevent burning. Once cooked, transfer the fish to a plate lined with paper towels to drain any excess oil. Break into smaller, taco-sized pieces.
Step 6: Warm the tortillas. Quickly char tortillas over an open flame on a gas stove, heat them in a dry skillet for about 30 seconds per side, or wrap them in damp paper towels and microwave for 30 seconds.
Step 7: Assemble your fish tacos! Lay out your warm tortillas. Place a generous amount of the crispy fish onto each tortilla. Top with a spoonful of the zesty slaw, a drizzle of the creamy taco sauce, and any optional toppings like avocado, extra cilantro, or a squeeze of lime. Serve immediately.