In a medium bowl, whisk together the olive oil, lime juice, chili powder, cumin, smoked paprika, garlic powder, onion powder, salt, and pepper until smooth and combined.

Cut the chicken thighs into bite-sized pieces, about 1-inch chunks. Add them to the bowl and toss well to coat every piece thoroughly. Cover the bowl with plastic wrap and refrigerate for at least 30 minutes, or up to 8 hours for deeper flavor.

Heat a large cast-iron skillet or heavy-bottomed pan over medium-high heat until hot. Add the marinated chicken pieces in a single layer, being careful not to overcrowd the pan (cook in batches if needed).

Cook the chicken for 4 to 6 minutes per side, until it is cooked through and has a nice char on the outside. The internal temperature should reach 165°F. Transfer the cooked chicken to a plate and tent with foil to keep warm.

Warm the corn tortillas one at a time in a dry skillet over medium heat for about 30 seconds per side, or directly over a gas flame using tongs until they are soft and pliable. Alternatively, stack them in a damp paper towel and microwave for 30 seconds.

To assemble, place a generous portion of the cooked chicken on each warm tortilla. Top with a sprinkle of diced white onion and fresh cilantro. Serve immediately with lime wedges on the side for squeezing over the tacos.