Slice the chicken breast and flank steak into thin, uniform strips across the grain for maximum tenderness.
In a medium bowl, toss the meat strips with half of the olive oil, chili powder, cumin, garlic powder, salt, and pepper until well coated.
Heat a large cast-iron skillet over medium-high heat and add the remaining olive oil to the pan.
Add the seasoned meat to the skillet in a single layer and sear until deeply browned and cooked through, approximately 5-6 minutes.
Remove the meat from the skillet and set aside on a plate; add the sliced bell peppers and red onions to the same pan.
Sauté the vegetables for 4-5 minutes until they are tender-crisp with charred, caramelized edges.
Return the meat to the skillet, drizzle with fresh lime juice, and toss everything together before garnishing with fresh cilantro.