Slice the chicken breast into thin, even 1/2-inch strips to ensure quick and uniform cooking.
Core the bell peppers and slice them into thin strips, then thinly slice the red onion into half-moons.
In a small bowl, whisk together the chili powder, ground cumin, sea salt, and black pepper.
Heat the extra virgin olive oil in a large cast-iron skillet over medium-high heat until the oil is shimmering.
Add the chicken strips to the skillet in a single layer and sprinkle with half of the spice blend, searing for 3-4 minutes until golden brown.
Flip the chicken, add the bell peppers and red onion, and sprinkle with the remaining spice blend and minced garlic.
Sauté for another 5-6 minutes, tossing frequently, until the vegetables are tender-crisp and the chicken is fully cooked through.
Remove the skillet from heat and immediately drizzle with fresh lime juice, scraping the bottom of the pan to release the flavorful browned bits.
Garnish with chopped fresh cilantro and serve immediately for a clean, high-protein meal.