In a mixing bowl, whisk together lime juice, orange juice, garlic, olive oil, cumin, smoked paprika, chili powder, salt, and black pepper.
Place the steak in a resealable bag or shallow dish. Pour the marinade over it, ensuring it’s fully coated. Let it marinate for at least 1 hour or up to overnight.
Preheat the grill to medium-high heat. Remove the steak from the marinade and pat dry to achieve a better sear.
Grill the steak for about 4-5 minutes per side for medium-rare, adjusting for desired doneness. Remove and let it rest for 10 minutes.
While the steak rests, grill the bell peppers and onions for 5-7 minutes, stirring occasionally, until slightly charred and softened.
Slice the steak thinly against the grain. Serve in warm tortillas with grilled peppers, onions, and fresh cilantro.