In a large pot, boil water and add the potato starch noodles to cook per package instructions (approx 6 minutes boiling). Strain the water, rinse under cold water, and set the noodles aside.
1 bundle Korean potato starch noodles
If you're vegetables aren't sliced already, slice the onion, julienne the carrot and zucchini, and cut the mushrooms to match the matchstick size of the other vegetables as best as possible (this will depend what mushroom you're using. For oyster mushrooms, use your hands to tear the mushrooms lengthwise into strips).
1 julienned carrot, 1/4 cup sliced onion, 1/2 cup julienned zucchini, 1/4 cup sliced mushrooms, 2 green onions
Cut the beef into small bite-sized strips too, as close to that matchstick size as well.
4 oz beef
Mix all the Japchae Sauce ingredients together and set aside.
2 TBSP gluten free tamari, 2 TBSP maple syrup, 2 TBSP sesame oil, 2 tsp garlic powder, 2 TBSP sake, 1 pinch black pepper, 1 TBSP roasted sesame seeds