In a mixing bowl, combine olive oil, chili powder, ground cumin, smoked paprika, garlic powder, lime zest, lime juice, sea salt, and black pepper. Whisk until well mixed. Add the white fish fillets and ensure they are fully coated in the marinade. Cover and let them marinate for 15-20 minutes in the refrigerator.

Prepare the slaw by tossing shredded green and red cabbage, grated carrot, and fresh cilantro in a large bowl. Drizzle lime juice and olive oil over the mixture, seasoning with sea salt to taste. Mix thoroughly until all vegetables are well combined.

In a separate bowl, whisk together sour cream (or Greek yogurt), mayonnaise, freshly chopped cilantro, lime juice, and a pinch of salt and pepper. Stir until smooth and creamy. Chill in the refrigerator until ready to serve.

Heat a non-stick skillet over medium-high heat. Once hot, add the marinated fish fillets to the skillet, cooking for 2-3 minutes on each side until golden brown and flaky. Remove from the skillet and set aside to cool slightly before flaking into large chunks.

Warm the corn tortillas until pliable. Assemble tacos by placing a scoop of slaw on each tortilla, followed by flaky fish chunks and sliced avocado. Drizzle with cilantro crema and serve immediately with lime wedges.