Place the chicken thighs in a large resealable plastic bag or a shallow bowl. Add the garlic powder, onion granules, cumin, paprika, chili powder, salt, pepper, lime juice, and olive oil. Seal the bag and massage to coat, or use tongs to mix if using a bowl. Let the mixture sit for up to 30 minutes to allow the flavors to infuse, or proceed immediately if pressed for time.

Warm a large skillet over medium to medium-high heat. Once heated, pour in a tablespoon of oil and arrange the chicken in the pan. Sear for approximately 12 to 14 minutes, flipping once halfway through, until the chicken is fully cooked. If using especially thick pieces, lower the heat to medium and extend cooking time up to 25 minutes, ensuring no pink remains.

As the chicken cooks, prepare the topping by combining the diced onion, chopped cilantro, minced jalapeño, and juice of one lime in a small mixing bowl. Add salt and pepper to taste and stir until evenly blended.

Once cooked, remove the chicken from the pan and allow it to rest for 10 minutes. Meanwhile, wipe the skillet clean with a damp cloth or paper towel and return it to medium-high or high heat. Place two tortillas stacked together in the skillet and heat until slight charring appears on the bottom. Flip and toast the other side. Continue this process with the remaining tortillas.

Dice the rested chicken into bite-sized chunks.

To assemble, place one portion (approximately 1/8) of the chopped chicken onto each double-stacked tortilla. Spoon over a generous helping of the onion-cilantro topping and finish with a lime wedge on the side for squeezing just before eating.