In a mixing bowl, combine olive oil, chili powder, ground cumin, smoked paprika, garlic powder, lime zest, lime juice, sea salt, and black pepper to create a zesty marinade. Add your choice of white fish—cod, tilapia, or haddock—and coat evenly. Allow the fish to marinate for 15-20 minutes at room temperature.

In a separate bowl, mix together the shredded green and red cabbage, grated carrot, and fresh cilantro. Drizzle with lime juice and olive oil, then sprinkle in some sea salt to taste. Toss everything until the vegetables are well coated and vibrant.

In a small mixing bowl, whisk together sour cream or Greek yogurt with mayonnaise, finely chopped cilantro, lime juice, garlic powder, and a pinch of salt and pepper. Blend until smooth and creamy. Cover the bowl and refrigerate the cilantro crema for a few minutes.

Preheat a non-stick skillet over medium-high heat. Once hot, add the marinated fish and cook for about 2-3 minutes per side, or until the fish is golden brown and flakes easily with a fork. Monitor closely to prevent overcooking.

Warm your corn tortillas on a skillet for about 30 seconds on each side until soft and pliable. On each tortilla, layer a generous scoop of the crunchy slaw, followed by pieces of flaky fish and slices of creamy avocado. Drizzle your chilled cilantro crema over the top, and add a sprinkle of fresh cilantro for garnish.