Dice the chicken breast into small, uniform bite-sized pieces to ensure even cooking and quick browning.
In a medium bowl, toss the chicken with the chili powder, ground cumin, sea salt, and black pepper until every piece is well-coated.
Heat the olive oil in a non-stick skillet over medium-high heat until shimmering, then add the chicken in a single layer.
Sauté the chicken for 6-8 minutes, stirring occasionally, until the exterior is golden-brown and the center is fully cooked through.
While the chicken cooks, mash the avocado in a small bowl with the finely diced red onion, chopped cilantro, and lime juice to create a chunky salsa.
Warm the corn tortillas in a dry pan or over an open flame for 30 seconds per side until they are soft and pliable.
Assemble the tacos by layering the shredded cabbage onto the warm tortillas, followed by a generous portion of the spiced chicken.
Finish each taco with a dollop of the fresh avocado salsa and an extra squeeze of lime if desired.