Prepare the Marinade:
In a mixing bowl, combine orange juice, lime juice, olive oil, garlic, cilantro, cumin, chili powder, smoked paprika, oregano, salt, pepper, and jalapeño (if using). Whisk until well mixed.
Marinate the Steak:
Place the flank or skirt steak in a ziplock bag or shallow dish. Pour the marinade over the steak, ensuring it is completely coated. Seal the bag or cover the dish and marinate in the refrigerator for at least 1 hour or up to 8 hours.
Preheat the Grill:
Heat your grill or grill pan to high heat (450°F/230°C). Lightly oil the grates to prevent sticking.
Grill the Steak:
Remove the steak from the marinade, letting any excess drip off. Grill for 4-5 minutes per side, or until the steak reaches your desired doneness.
Medium-rare: 130-135°F (54-57°C)
Medium: 140-145°F (60-63°C)
Rest and Slice:
Let the steak rest for 5-10 minutes to lock in the juices. Slice thinly against the grain for maximum tenderness.
Serve:
Serve the carne asada with warm tortillas, fresh salsa, guacamole, lime wedges, and your favorite toppings.