Slice the chicken breast into thin strips and place them in a medium mixing bowl.
Slice the bell peppers and red onion into thin strips and add them to the bowl with the chicken.
Drizzle the olive oil over the chicken and vegetables, then sprinkle with ground cumin, chili powder, garlic powder, sea salt, and black pepper.
Toss everything together until the chicken and vegetables are evenly coated in the oil and spices.
Heat a large cast-iron skillet over medium-high heat and add the chicken and vegetable mixture in a single layer.
Cook for 8-10 minutes, stirring occasionally, until the chicken is cooked through and the vegetables are tender with charred edges.
Place the chopped romaine lettuce into a serving bowl as the base.
Top the lettuce with the cooked chicken and roasted pepper mixture.
Garnish with sliced avocado, a squeeze of fresh lime juice, and chopped fresh cilantro before serving.