Preheat the oven to 220°C (425°F) with a rack in the upper third. Line a large rimmed baking sheet with parchment.
Slice the chicken into strips about 1 cm (1/2 inch) thick so they cook at the same rate as the vegetables. Slice the peppers and red onion.
Toss the chicken, peppers and onion with the oil, chili powder, cumin, smoked paprika, garlic powder and salt, and spread in a single layer. Use two trays if crowded, or the vegetables will steam.
Roast for 18 to 20 minutes, stirring once halfway, until the vegetables are charred at the edges and the chicken reaches 74°C (165°F).
Warm the tortillas wrapped in foil in the oven for the last 5 minutes.
Squeeze the lime over the tray and serve in the warm tortillas with Greek yogurt, salsa and cilantro.
Tips
Use two trays if crowded; overcrowding steams instead of roasts.