Pat the chicken breast dry with a paper towel and dice into 1/2-inch cubes for even cooking.
In a small bowl, mash the avocado with the Greek yogurt and half of the lime juice until the texture is smooth and velvety.
Season the diced chicken thoroughly with the chili powder, cumin, sea salt, and black pepper.
Heat the extra virgin olive oil in a large skillet over medium-high heat until shimmering.
Add the chicken to the skillet in a single layer and sear for 6-8 minutes, stirring occasionally, until deeply browned and cooked through.
While the chicken sears, toss the shredded cabbage with the remaining lime juice, finely diced red onion, and chopped cilantro.
Briefly toast the corn tortillas over an open flame or in a dry pan until warm and slightly charred.
To assemble, divide the chicken among the tortillas, top with the cabbage slaw, and finish with a generous dollop of avocado crema.