Preheat an outdoor grill or grill pan to medium-high heat.
In a small bowl, combine the chili powder, cumin, smoked paprika, minced garlic, salt, and black pepper. Rub the seasoning mixture over the steak.
Coat the steak with 1 teaspoon of canola oil. Grill for 4–5 minutes per side for medium-rare, or until it reaches your preferred doneness.
Transfer the steak to a cutting board and let it rest for 5 minutes.
Toss the bell peppers and red onion with the remaining oil. Season lightly with salt and pepper.
Grill the vegetables for 6–8 minutes, turning occasionally, until browned and tender.
Slice the steak thinly across the grain. Serve with the grilled peppers and onion in warm tortillas, with pico de gallo and guacamole if desired.