Make the beef marinade by mixing the listed ingredients. Save a 1/3 of the sauce in a separate bowl - we will use it later
Place the remaining 2/3 of the sauce in a mixing bowl. Cut skirt steak into a finger's length and place them into the marinade in the mixing bowl.
Bring a pot of water to boil. Quickly blanche the Oyster and Shiitake mushrooms for 30 seconds. Give them a quick rinse in cold water. Squeeze out the water from each mushroom. Set Oyster mushroom aside. We will marinate the Shiitake mushrooms.
Pour the remaining 1/3 marinade over the Shiitake mushrooms. Set Shiitake mushrooms aside. Then place a frying pan on medium-high heat and quickly sear the beef pieces (no need to cook completely through).
Cut bell peppers and spring onion into finger's length. Then cut the marinated Shiitake Mushrooms into similar length.
Then place each one of the ingredients onto the toothpick. You can use more-or-less of any specific ingredients - but try to get a nice balance in color.
Then set aside each completed pancake for the egg-wash (skip to step 3, when ready to cook)