Place the flank steak in a re-sealable plastic bag. Pour in the orange juice, lime juice, and salt. Mix everything around and remove as much air as possible before sealing the bag shut. Allow the steak to marinate in the fridge for at least 2 hours, up to overnight.

Preheat a grill for direct grilling of at least 450°F. Clean the grates as needed.

Remove the steak from the bag and pat it dry. Apply the BBQGuys x Spiceology Beef Rub generously on both sides, patting the seasoning into the meat.

Grill the steak directly over the coals. Flip every 2 minutes, building a nice crust on the outside. Clean the grates as needed between flips. Cook until the meat is about 10 degrees before target temperature, 125-130°F for a target of medium-rare.

Allow the meat to rest on a baking sheet with loosely tented foil for about 10 minutes. Dice up the onion and cilantro while the steak is resting.

Warm up the tortillas and serve the tacos with the cubed steak, toppings, and salsa. Cheers!