Cut the steak into thin strips and place them in a large zip lock bag.
Stir together the liquid aminos (or soy sauce), pure maple syrup, sesame oil, garlic, ginger, gochujang and black pepper in a small bowl or measuring cup until well-combined.
Pour this marinade into the zip lock bag with the beef. Seal the bag and move everything around until the beef is well-coated in the marinade. Refrigerate for two hours, or up to 24 hours.
When you’re ready to cook the beef, heat a large skillet over medium-high heat and add the avocado oil. Once the skillet is sizzling hot, carefully place half of the strips of beef on the hot surface in a single layer, giving each piece plenty of space to cook.
Sear for 2 to 3 minutes, or until golden brown and crispy, then flip the steak strips using tongs and sear another 2 to 3 minutes. Transfer the steak to a plate and repeat for the remaining steak.
Once all of the steak is seared, transfer the other half back to the skillet and add the remaining marinade leftover in the zip lock. Bring to a full boil and cook for 3 to 5 minutes, until everything is heated through.
Serve bulgogi beef over steamed white rice or brown rice and spoon the sauce over everything. For a low-carb version, use butter lettuce to make lettuce wraps or serve with cauliflower rice. Serve with sesame seeds and fresh chopped green onions.