Slice the chicken breast into thin strips and place them in a small bowl.
Toss the chicken with chili powder, cumin, garlic powder, sea salt, and black pepper until evenly coated.
Heat the olive oil in a large cast-iron skillet over medium-high heat until shimmering.
Add the seasoned chicken strips to the skillet in a single layer and sear for 3-4 minutes per side until golden brown and cooked through.
Remove the chicken from the skillet and set aside; add the sliced bell peppers and red onions to the same pan.
Sauté the vegetables for 5-6 minutes until they are tender-crisp with slightly charred edges.
Return the chicken to the skillet, drizzle with fresh lime juice, and toss everything together to combine.
Serve immediately topped with sliced avocado and a sprinkle of fresh cilantro.