Slice the chicken breast into thin strips and place them in a small bowl.
Whisk together the chili powder, cumin, smoked paprika, garlic powder, sea salt, and black pepper, then toss with the chicken to coat evenly.
Heat the olive oil in a large skillet over medium-high heat.
Add the seasoned chicken strips to the skillet and cook for 5-6 minutes until golden brown and cooked through.
Add the sliced red bell pepper, green bell pepper, and red onion to the skillet with the chicken.
Sauté the vegetables for 3-4 minutes until they are tender-crisp and slightly charred.
Pour the lime juice over the chicken and vegetable mixture, stirring to deglaze the pan and incorporate the flavors.
Place the cooked brown rice in the base of a serving bowl.
Top the rice with the chicken and fajita vegetable mixture.
Finish the bowl with fresh avocado slices and a garnish of chopped cilantro.