In a medium bowl, whisk together mayonnaise or plain yogurt, taco seasoning, and fresh lime juice until smooth. Add in the shredded cabbage, grated carrots, chopped green onions, and cilantro, tossing well to coat.

Pat dry the cod fillets with paper towels and season with additional taco seasoning. Heat a skillet over medium-high heat and add olive oil. Once shimmering, place the fish in the pan, cooking for about 4 minutes on each side.

In the same skillet, add a drizzle of olive oil and toss in chopped red onion, red bell pepper, and diced jalapeño. Sauté for 1 minute until fragrant. Stir in frozen corn and drained black beans, cooking for another 1-2 minutes.

To assemble, add a scoop of slaw to the bottom of serving bowls, top with flaky cod, add salsa, and layer with sliced avocado. Serve with lime wedges and cilantro.