In a non-reactive glass bowl or heavy-duty resealable bag, whisk together lime juice, orange juice, soy sauce, minced garlic, olive oil, cumin, chili powder, oregano, salt, and pepper.

Submerge the steak in the marinade, ensuring total surface contact. Seal and refrigerate for a minimum of 4 hours, ideally up to 8 hours, to allow enzymatic tenderization and flavor penetration.

Remove steak from refrigeration 30 minutes prior to cooking to reach ambient temperature. Pat the surface dry with paper towels to facilitate Maillard browning.

Preheat a cast-iron grill pan or outdoor gas grill to high heat (approximately 450°F to 500°F / 230°C to 260°C).

Place the steak on the high-heat surface. Sear for 4 to 5 minutes per side for medium-rare doneness (target internal temperature of 135°F / 57°C).

Transfer the steak to a clean cutting board and tent loosely with foil. Allow the proteins to rest for 10 minutes to redistribute internal juices.

While the meat rests, warm the corn tortillas directly over a gas flame or in a dry skillet for 30 seconds per side until pliable and slightly charred.

Carve the steak across the grain into thin strips, then rotate 90 degrees and dice into 0.25-inch cubes.

Assemble the tacos by placing approximately 2 ounces of diced beef onto each double-stacked tortilla pair.

Garnish each taco with diced white onion, chopped cilantro, and two slices of radish. Serve immediately with lime wedges for manual acidity adjustment.