In a small bowl, combine the marinade ingredients: Smoked paprika, vegetable oil, lime juice, minced garlic, chili powder, cumin powder, cayenne pepper powder, and salt. Use a whisk to combine well.
Place the fish fillets in a ziplock or freezer bag (you may need to use more than one), and pour in the marinade. Seal the bag and place it in the refrigerator for 30-60 minutes.
In another bowl, combine the crema sauce ingredients. Place in refrigerator.
Fire up your grill to medium heat, about 300-375°F (150-190°C)
Remove fish fillets from the marinade. Pat excess marinade from the fillets with dry paper towels.
Once grill has fully warmed up, place the fish fillets on the grill (for best results, use a grill basket). Grill for 2-3 minutes on each side. The cod will be done when they have turned opaque and flake with little resistance when pressed with a fork.
Move fish to counter surface or chopping block and leave to rest for 2-3 minutes. Chop up fillets into small chunks or slices.
Warm corn tortillas on the grill grates for about 10 seconds on each side.
Serve the sliced fish on tortillas. Top with your choice of shredded red cabbage, pico de gallo, crema sauce, guacamole, sliced red onion, and chopped cilantro.