In a large mixing bowl, thoroughly combine the chicken with large pinch of salt, the black pepper, the chili powder and the cumin. Set the chicken aside while you get your vegetables started.
Heat the olive oil over high heat in the largest nonstick skillet youve got. Add the peppers and onion, and cook, stirring now and then, until theyre beginning to soften, about 5 minutes. Add the seasoned chicken to the pan and cook on high, stirring now and then, until the chicken and vegetables are cooked though and nicely browned, 15 minutes,
Meanwhile, warm the tortillas. Serve them with the chicken and all the toppings and let everyone mix and match.