Prepare the Slaw: In a medium bowl, whisk together mayonnaise (or yogurt) with taco seasoning and fresh lime juice until smooth. In a larger mixing bowl, combine shredded white and red cabbage, finely shredded carrots, chopped green onions, and cilantro. Drizzle a portion of the creamy dressing over the vegetables, tossing until evenly coated. Reserve the remaining dressing for serving and set the slaw aside.

Cook the Fish: Pat the cod fillets dry with paper towels. Brush both sides with olive oil and season with taco seasoning. Heat a skillet over medium-high heat and place the fish in the hot skillet. Cook for about 4 minutes until they easily release from the pan. Flip and cook for another 3-4 minutes until golden brown and flaky. Keep warm by covering with foil.

Make the Salsa: In the same skillet, add olive oil and sauté red onion, red bell pepper, and jalapeño for about 1 minute. Incorporate frozen corn and black beans, seasoning with salt. Cook until heated through. Remove from heat, squeeze lime juice, and toss to combine.

Assemble the Bowls: Distribute the prepared slaw in serving bowls, layer with salsa, place a cod fillet on top, and garnish with avocado slices, lime wedges, and fresh cilantro.