Preheat grill to medium-high heat.

In a bowl, combine olive oil, lime juice, cumin, chili powder, garlic powder, salt, and black pepper.

Coat chicken breasts with the spice mixture.

Grill chicken for about 6-7 minutes on each side or until cooked through.

Remove chicken from grill and let it rest for a few minutes.

Slice the grilled chicken into thin strips.

Warm the corn tortillas on the grill for about 30 seconds on each side.

Assemble tacos by placing chicken strips on tortillas and topping with shredded lettuce, diced tomatoes, red onion, cilantro, sour cream, and salsa.