Mix all marinade ingredients in bowl. Add steak, cover and refrigerate while preparing other ingredients.
Remove large stems from spinach. Rinse spinach in cold water and without draining, place in microwaveable bowl. Cover, vented, and microwave on high for 2-3 minutes, until wilted. Rinse with cold water and drain. Set aside.
Cook noodles in boiling water according to package directions. Place in colander and rinse with cold water for 1 minute. Drain. Cut into serving-size pieces and set aside.
Heat a wok or non-stick skillet and add 1 Tbs. vegetable oil. Stir fry the carrots for 5 minutes, then add the onions and bell pepper. Stir fry several minutes more then add bok choy, scallions, and garlic. Add more oil as needed. When vegetables are cooked, yet crisp, combine with spinach in large bowl.
Heat 1 Tbs. sesame oil in wok. Add drained noodles and 2 Tbs. soy sauce. Mix and heat through. Pour over vegetable mix.
Drain marinade from steak and discard. Heat and oil the wok and stir fry meat, 1/2 at a time. Add cooked meat to other ingredients. Add toasted sesame seeds and 2 Tbs. soy sauce. Mix and add additional salt, pepper, or soy sauce if needed.