To a small bowl add half the oil, lime juice, cumin, garlic, oregano, chili powder, paprika, crushed red pepper flakes, and salt. Mix well and set aside.
Slice the chicken into thin slices. Place chicken in a bowl with the marinade. Mix with your hands. Cover and refrigerate at least one hour, but not more than four hours.
Slice the bell peppers and white onion into half-inch slices. Slice the green tops of the scallions into thin 2 inch-long strips.
Place the onion and peppers on a hot grill pan with the remaining oil. Toss with tongs to cook. Add the scallions at the last minute of cooking.
Pour off and discard any marinade remaining in the bowl. Use tongs to place the chicken strips onto the hot grill pan.
Cook until the chicken is cooked through (165) degrees). Add the vegetables to the grill pan and toss until heated through.
When everything is heated through, leave the fajitas on the grill pan (no heat) until the tortillas are ready and it is time to serve. Remove the fajitas and place in a serving bowl.
In a separate frying pan, brush oil in a thin layer and grill the flour tortillas until soft with bits of brown. Wrap in foil and place in a 250 degree oven to keep warmuntil all are done.
Place the fajita mixture onto a warm tortilla. Top with guacamole, pico de gallo, sour cream, Oaxaca cheese, and cilantro. Squeeze a lime wedge over the top and sprinkle lightly with Cotija cheese. Enjoy!