Slice the steak against the grain into 1/2-inch thick strips.

In a large mixing bowl, whisk together lime juice, orange juice, olive oil, minced garlic, cumin, chili powder, oregano, paprika, salt, and pepper until smooth.

Add the steak strips to the marinade and toss to coat all pieces evenly.

Cover the bowl and refrigerate for at least 1 hour, up to 2 hours for maximum flavor.

Remove the marinated steak from the refrigerator 15 minutes before cooking to bring it to room temperature.

Preheat your grill, grill pan, or cast iron skillet over high heat until it is smoking hot, about 5 minutes.

Working in batches, place the steak strips on the hot surface and cook undisturbed for 2 to 3 minutes per side for medium-rare.

Use a meat thermometer to ensure the internal temperature reaches 130°F to 135°F.

Transfer the cooked steak to a serving platter and let it rest for 5 minutes.

While the meat rests, warm the tortillas on the grill or over an open flame for about 30 seconds per side.

Assemble the tacos by placing sliced steak on warm tortillas and topping with diced onion, cilantro, lime wedges, guacamole, and salsa as desired.