Pat the chicken breasts dry with paper towels to remove excess moisture for a better sear.

In a small bowl, mix cumin, chili powder, garlic powder, onion powder, oregano, cayenne, salt, and black pepper, then rub evenly over both sides of each chicken breast.

Heat a large skillet over medium-high heat for one minute, then add vegetable oil and heat until shimmering.

Place chicken breasts in the hot skillet and cook undisturbed for 3 to 4 minutes to form a golden crust.

Flip the chicken and cook for an additional 3 to 4 minutes until golden and the internal temperature reaches 165°F (74°C).

Squeeze the juice of two limes over the chicken in the pan, remove from heat, and let rest for 2 minutes to reabsorb juices.

Transfer chicken to a cutting board and shred with two forks or chop into bite-sized pieces.

Warm tortillas by holding each directly over a gas flame for about 5 seconds per side or wrapping in a damp towel and microwaving for 30 seconds.

Assemble tacos by placing shredded chicken on each warm tortilla and topping with diced onion, chopped cilantro, and lime wedges for serving.