In a small bowl, whisk together the olive oil, chili powder, cumin, garlic powder, and sea salt.
Rub the spice mixture evenly over all sides of the chicken breast.
Preheat a grill or grill pan over medium-high heat and cook the chicken for 6-7 minutes per side until charred and the internal temperature reaches 165°F.
While the chicken rests, toss the shredded cabbage, chopped cilantro, and finely diced red onion with a squeeze of fresh lime juice.
Slice the rested chicken into thin strips or small bite-sized cubes.
Briefly warm the corn tortillas on the grill or in a dry pan for 30 seconds per side until soft and pliable.
Assemble the tacos by dividing the chicken among the tortillas, then topping with the cabbage slaw, avocado slices, and salsa verde.