In a medium shallow bowl, whisk olive oil, lime juice, paprika, chili powder, cayenne, and cumin. Add cod and toss until coated. Let marinate 15 minutes.
In a larg nonstick skillet over medium-high heat, heat vegetable oil. Remove cod from marinade; season both sides of fish with salt and black pepper. Arrange fish in skillet flesh side down. Cook, turning once, until opaque and cooked through, 3 to 5 minutes per side. lest rest 5 minutes before flaking with a fork.
Top torillas with fish, corn slaw, and avocado. Squeeze lime juice over and drizzle with sour cream.