Dice the chicken breast into small, even bite-sized pieces.
In a small bowl, combine the chili powder, cumin, garlic powder, cayenne pepper, sea salt, and black pepper.
Toss the diced chicken in the spice blend until thoroughly coated.
Heat the olive oil in a large non-stick skillet over medium-high heat.
Add the seasoned chicken to the skillet and sauté for 5 to 6 minutes, stirring occasionally, until the chicken is golden brown and cooked through.
Add the rinsed and drained black beans to the skillet with the chicken, stirring for 2 minutes until the beans are heated through.
While the chicken and beans finish, warm the corn tortillas in a dry pan over medium heat for 30 seconds per side until soft and pliable.
Slice the avocado and finely chop the fresh cilantro.
Assemble the tacos by dividing the spicy chicken and bean mixture evenly between the two warm tortillas.
Top each taco with a dollop of Greek yogurt, avocado slices, fresh cilantro, and a drizzle of lime juice before serving.