Preheat the broiler. In a small bowl, whisk the oil, chili powder and garlic; season the spiced oil with salt and pepper.
On a rimmed baking sheet, coat the steak, bell pepper and onion with the spiced oil; season.
Broil, turning once, until the vegetables are browned in spots and the meat is charred and cooked to desired doneness, 8 to 10 minutes for medium-rare.
Loosely cover the steak with foil. Let rest 10 minutes before slicing thinly against the grain.
Serve the steak and vegetable mixture with the tortillas, pico de gallo and cilantro.