Mix the marinade ingredients together, then add in the beef, ensuring that the marinade is coating all sides of the beef. Put in fridge to marinade for 2-4 hours or overnight.
Put all the guacamole ingredients into a mortar and pestle and mash thoroughly. If you don’t have a mortar and pestle, you can mash the ingredients in a bowl using forks.
Heat a cast iron skillet to high heat. Place the beef pieces on the pan and cook on both sides until at desired doneness. My beef slices were relatively thin so I did about 1 minute on each side. Set aside for 5 minutes to allow the juices to flow back.
Sauté minced garlic, onion and mushrooms. Once the vegetables have begun to soften, about 3-4 minutes, remove from heat.
At this point, it’s time to assemble the taco. Cut the beef pieces into small bite-sized pieces. Then a large pan, lay down tortilla and cheese. Cook until cheese is melted.
Layer the taco with the sautéed veggies, beef, and guacamole.
Fold the taco in half. If the other side is not at desired toasty-ness, flip over to let it cook.
Remove from heat and enjoy your delicious fusion creation!