Marinate the Chicken
In a bowl, whisk olive oil, lime juice, garlic, chili powder, cumin, smoked paprika, oregano, salt, and pepper. Add chicken and toss to coat evenly. Marinate for at least 30 minutes.
Cook the Chicken
Heat a large skillet over medium-high heat. Add chicken in a single layer and cook for 5–7 minutes per side until cooked through and lightly charred.
Rest & Slice
Transfer chicken to a cutting board and rest for 5 minutes. Slice into small taco-sized pieces.
Warm Tortillas
Warm tortillas in a dry skillet or directly over a flame until soft and lightly blistered.
Assemble
Fill tortillas with chicken, then top with onion, cilantro, and a squeeze of lime. Add sauce if desired.