01 - In a shallow bowl, whisk together olive oil, lime juice, cumin, paprika, garlic powder, salt, and black pepper until well combined.
02 - Add fish fillets to the marinade, turning to coat evenly. Let sit at room temperature for 15 minutes to absorb flavors.
03 - Heat grill to medium-high temperature. Lightly oil the grates to prevent sticking.
04 - Place marinated fish on the grill. Cook for 3 to 4 minutes per side until fish is opaque throughout 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. Mix until smooth and refrigerate until ready to serve.
06 - Place corn tortillas on the grill for 30 seconds per side until warmed and pliable. Stack on a plate and cover with a clean towel to keep warm.
07 - Using a fork, flake the rested grilled fish into large chunks, discarding any skin or bones.
08 - Layer shredded cabbage, flaked fish, diced tomatoes, avocado slices, crumbled cheese, and fresh cilantro on each tortilla. Drizzle generously with the cream sauce.
09 - Arrange tacos on a serving platter with lime wedges on the side. Serve immediately while tortillas are warm and fish is hot.