Slice the chicken breast into thin, even strips and place them in a bowl.
Toss the chicken strips with the chili powder, ground cumin, garlic powder, sea salt, and black pepper until well coated.
Heat the extra virgin olive oil in a large cast-iron skillet over medium-high heat until shimmering.
Add the seasoned chicken to the skillet and cook for 5-6 minutes, stirring occasionally, until golden brown and cooked through.
Remove the chicken from the skillet and set aside on a plate.
In the same skillet, add the sliced bell peppers and red onion, sautéing for 4-5 minutes until they are tender-crisp with slight charred edges.
Return the cooked chicken to the skillet, drizzle with fresh lime juice, and toss everything together for 1 minute to combine flavors.
Serve the fajita mixture hot, topped with sliced avocado and a dollop of plain Greek yogurt.