Preheat the oven to 425°F and line a large sheet pan with parchment paper or foil for easy cleanup.
Place the chicken strips, sliced bell peppers, and sliced red onion in a large mixing bowl.
Drizzle the olive oil over the mixture, then sprinkle in the fajita seasoning mix and salt. Toss everything until evenly coated.
Spread the chicken and vegetables in a single layer on the prepared sheet pan. Avoid crowding so the pieces roast instead of steam.
Bake for 20 to 25 minutes until the chicken reaches 165°F and the vegetables are tender with some browned edges.
While the sheet pan finishes, warm the flour tortillas in a dry skillet or wrapped in foil in the oven for the last 3 minutes.
Remove the pan from the oven and serve the fajita mixture with the warm tortillas, lime wedges, and chopped cilantro.