In a medium bowl, whisk together olive oil, lime juice, paprika, chili powder, and cayenne
Add cod, tossing until evenly coated
Bake cod for 8-10 minutes until fully cooked
Let cod rest for 5 minutes before flaking with a fork
Assemble tacos by adding fish and topping with onions, cheese and sour cream
Squeeze fresh lime juice on top of fish tacos