In a large bowl, whisk together olive oil, lime juice, minced garlic, ground cumin, chili powder, salt, and black pepper.
Add the chicken thighs to the bowl and coat them evenly with the marinade. Cover and let marinate in the refrigerator for at least 30 minutes or up to 2 hours for more flavor.
Preheat a grill or grill pan over medium-high heat. Remove chicken from marinade and grill for about 5-7 minutes on each side or until fully cooked and internal temperature reaches 165°F (75°C). Once cooked, let the chicken rest for a few minutes before slicing.
While the chicken is resting, warm the corn tortillas on a dry skillet over medium heat for about 30 seconds on each side until they are pliable.
Slice the grilled chicken into strips and toss with fresh chopped cilantro.
Assemble the tacos: place a few strips of chicken on each tortilla, top with shredded cabbage or lettuce, avocado slices, and salsa or pico de gallo.
Garnish with extra cilantro, if desired, and squeeze a little more lime juice over the assembled tacos for a zesty finish.
Notes
Serve the tacos on a colorful platter with lime wedges on the side for an appealing presentation. You can also wrap some parchment paper around the base of the tacos for a fun street-food look!