Preheat the oven to 400°F (200°C) and lightly grease a baking sheet with nonstick spray.
In a large bowl, combine the diced roma tomatoes, sliced yellow onion, and sliced bell peppers; spread the vegetables in an even layer on the prepared baking sheet.
In a small bowl, stir together the Greek yogurt, fajita seasoning, and minced cilantro to make a coating sauce.
Add the chicken strips to the yogurt mixture and toss until the chicken is fully coated.
Place the coated chicken strips on the baking sheet with the vegetables, arranging everything in a single layer for even cooking.
Bake uncovered for 20–25 minutes, or until the chicken is cooked through and the vegetables are fork-tender.
With about 8 minutes remaining, wrap the tortillas in foil and place them in the oven to warm.
Serve the chicken and vegetables with warmed tortillas and optional garnishes: queso fresco, extra cilantro, lime wedges, and a dollop of Greek yogurt.