In a mixing bowl, combine chili powder, cumin, paprika, salt, and pepper. Coat the boneless chicken thighs evenly and marinate for at least 15 minutes.

While the chicken marinates, prepare the guacamole by mashing the avocados and mixing in lime juice and a pinch of salt.

Finely dice the white onion and chop the fresh cilantro. Crumble the queso fresco and cut lime into wedges.

Heat a large skillet over medium heat. Cook marinated chicken thighs for 6-8 minutes on each side until well-charred and cooked through.

Warm the corn tortillas on a dry skillet for about 30 seconds on each side until pliable.

Assemble the tacos by slicing the cooked chicken, placing it on the tortillas, and topping with guacamole, onion, cilantro, and queso fresco.