1. In a mixing bowl, combine chili powder, cumin, paprika, garlic powder, salt, olive oil, and lime juice. Add fish fillets and coat well. Let marinate for 15 minutes.
2. Heat a skillet over medium-high heat. Cook the fish for 3-4 minutes on each side until cooked through and flaky. Remove from heat and break into chunks.
3. In a small bowl, whisk together sour cream, lime juice, lime zest, chopped cilantro, and salt to make the lime sauce.
4. Warm the tortillas in a dry skillet or microwave. Assemble the tacos by placing fish chunks on each tortilla, topping with shredded cabbage, diced tomatoes, and chopped cilantro. Drizzle with lime sauce and serve with lime wedges.