In a bowl, whisk together olive oil, lime juice, chili powder, cumin, garlic powder, onion powder, oregano, cayenne pepper (if using), salt, and black pepper.
Add chicken pieces to the marinade and coat evenly. Cover and refrigerate for at least 30 minutes (up to 4 hours for best flavor).
Heat a skillet over medium-high heat with a tablespoon of olive oil. Cook marinated chicken in batches until golden brown (about 3-4 minutes per side).
Warm tortillas in a dry skillet for about 15-20 seconds each side until pliable.
Assemble tacos by adding cooked chicken and your choice of toppings like chopped onion and cilantro.