01 - Whisk together olive oil, lime juice, cumin, paprika, garlic powder, salt, and pepper in a shallow bowl until thoroughly combined.
02 - Add fish fillets to the bowl, turning to coat evenly. Let marinate at room temperature for 15 minutes, turning once halfway through.
03 - Heat grill to medium-high temperature (approximately 400°F). Lightly oil the grates to prevent sticking.
04 - Place fish on the grill and cook for 3-4 minutes per side until just cooked through and flakes easily with a fork. Transfer to a plate and let rest for 5 minutes.
05 - While fish grills, combine sour cream, lime juice, chopped cilantro, salt, and pepper in a small bowl. Stir until smooth and refrigerate until serving.
06 - Place tortillas directly on the grill for 30 seconds per side until warm and pliable. Wrap in a clean towel to keep warm.
07 - Using a fork, flake the rested fish into large chunks, discarding any skin or bones.
08 - Layer each tortilla with red cabbage, fish, tomatoes, avocado, cheese, and cilantro. Drizzle generously with the cream sauce.
09 - Arrange tacos on a platter with lime wedges on the side. Serve while warm for best texture and flavor.