First, bring some water to a boil, turn off the heat, and put in the noodles to soak for 30 minutes.
Marinate the beef and mushrooms for 20 minutes by whisking together the marinade ingredients and adding the beef and mushrooms.
While the beef is marinating and the noodles soaking, julienne the carrots. Wash the spinach. Cut the green parts of the scallions into 2 inch pieces.
In a big pan, add the 2 tablespoons of sesame oil, put on high heat and once hot, cook the mushrooms and beef for 2 minutes. Then, add the spinach, onion, scallions and carrots. Stir for another minute or two until the vegetables are soft and the beef is cooked through. Turn off the heat.
Drain the noodles, cut them in half with kitchen shears, then add them to the pan. Mix with the vegetables while adding 1 teaspoon of sesame seeds and 1 tablespoon of soy sauce. Put on a nice serving platter.