Warm the beef broth that you've reserved from cooking the barbacoa beef. Heat a large non-stick griddle over medium-high heat.
To prepare the tortillas, carefully dip them in the broth to coat using tongs. Place on the hot griddle to warm, about 60-90 seconds per side. Fill the tortillas with the barbacoa beef and any additional toppings then gently fold in half and continue to heat until warmed through and/or cheese is melted (if using.) Serve warm.