Heat & prep pan - Position a rack in the top third of the oven and preheat to 425°F. In a small bowl, combine the seasonings and set aside.
Spread veggies and chicken over a rimmed sheet pan and drizzle with olive oil. Sprinkle on the seasoning mix and toss everything to evenly coat in seasoning. Spread evenly over the pan and let rest 10 minutes at room temp (or refrigerate up to 2 hours) for deeper flavor.
Bake 18-20 minutes, then switch to broil for 2-3 minutes or until the edges are browned and lightly charred, and the chicken registers 165°F.
Warm tortillas - Wrap tortillas in a sheet of foil and set them in the oven for the last 5 minutes of bake time.
Garnish & serve - Squeeze fresh lime juice over the fajitas and sprinkle cilantro over the top if desired. Build fajitas with tortillas and add your favorite toppings.
