In a medium bowl, combine the chili powder, cumin, smoked paprika, garlic powder, oregano, salt, and pepper. Toss the sliced chicken strips with half of this seasoning mix.
Heat 1 tablespoon of olive oil in a large skillet or cast-iron pan over medium-high heat until shimmering. Add the seasoned chicken in a single layer, avoiding overcrowding. Sear the chicken for 3-4 minutes per side until browned and cooked through, aiming for crispy edges. Remove the chicken from the skillet and set aside.
Add the remaining 1 tablespoon of olive oil to the same skillet. Add the sliced onions and peppers. Sauté over medium-high heat for 5 to 7 minutes, stirring occasionally, until the vegetables are tender-crisp.
Return the cooked chicken to the skillet with the vegetables. Sprinkle the remaining half of the seasoning mix over the chicken and vegetables. Toss everything together.
Squeeze the lime juice over the mixture and cook for 1 minute more until heated through.
Warm the tortillas according to package directions. Serve the crispy chicken and pepper mixture immediately in the warm tortillas with your desired toppings.
Notes
For extra crispiness, ensure your skillet is very hot before adding the chicken, and do not move the chicken until a sear forms.
If you prefer softer peppers, cover the skillet for the last two minutes of sautéing.
You can prepare the seasoning blend ahead of time for faster assembly.