In a small bowl, stir together cumin, chili powder, onion powder, salt, and red pepper flakes. Season both sides chicken breasts with half of the seasoning mixture, reserving the other half for later.
Heat a large skillet over medium-high heat. Add in 1 tablespoon of olive oil. Cook the chicken in the skillet for 5 to 7 minutes per side, until chicken is fully cooked through and reaches an internal temperature of 165 degrees F.
Remove the chicken breasts from the pan and set aside to rest.
Add remaining 1 tablespoon of olive oil to the skillet, let heat for a minute, and then add in your sliced bell peppers and onion. Saute until the vegetables are tender crisp, 5 to 7 minutes
During the last two minutes of cooking add in the remaining half of your seasoning mix and the minced garlic. Cook an additional 1 to 2 minutes.
Slice the chicken breasts into long strips and return them to the skillet with the vegetables.
Drizzle with lime juice and toss together. Serve on a warm tortilla. Serve plain or top with sour cream, cilantro, guacamole, or salsa.