01 - Whisk together olive oil, lime juice, cumin, smoked paprika, garlic powder, salt, and black pepper in a shallow bowl until well combined.
02 - Add fish fillets to the marinade, turning to coat evenly. Let stand for 15 minutes at room temperature.
03 - Heat grill to medium-high temperature (approximately 400°F). Lightly oil the grates to prevent sticking.
04 - Place marinated fish on the grill. Cook for 3-4 minutes per side until fish is opaque and flakes easily with a fork. Remove and let rest for 5 minutes.
05 - Combine sour cream, lime juice, chopped cilantro, salt, and pepper in a small bowl. Mix until smooth and refrigerate until serving.
06 - Place corn tortillas on the grill for 30 seconds per side until warmed and slightly charred. Stack and wrap in a clean towel to keep warm.
07 - Break rested fish into large flakes using a fork, discarding any bones.
08 - Layer red cabbage, flaked fish, diced tomatoes, avocado slices, crumbled cheese, and fresh cilantro on each warm tortilla.
09 - Drizzle with prepared cream sauce and serve immediately with lime wedges on the side.