In a mixing bowl, combine olive oil, cumin, paprika, garlic powder, salt, black pepper, and lime juice. Add the chicken breasts and coat well. Marinate for at least 30 minutes.

Preheat the grill to medium-high heat. Remove the chicken from the marinade and grill for about 6-7 minutes on each side, or until fully cooked and internal temperature reaches 165°F (75°C).

Once the chicken is cooked, let it rest for a few minutes before slicing it into thin strips. Warm the corn tortillas on the grill for about 30 seconds on each side.

Assemble the tacos by placing sliced chicken on each tortilla and topping with shredded lettuce, diced tomatoes, sour cream, shredded cheese, and cilantro.