Make the teriyaki sauce and set it aside while you cook the rest.
Cook noodles according to package directions, drain and rinse well.
Peel and chop all of the vegetables that you wish to use. It should total about 3-4 cups of veggies. (I usually cut them into skinny match stick sized shapes).
Pour 2 tbsp of sesame oil at the bottom of a large frying pan or wok and toss in the sliced onion. Sprinkle with a little salt and cook over low heat until slightly translucent.
Turn up the heat and toss in the remaining vegetables stirring them frequently for about 5-7 minutes until they are tender.
Drain and rinse the noodles and dump them in with the veggies. Add an additional 2 tbsp of sesame oil and toss all together.
Pour the teriyaki sauce over the veggies and noodles, toss again, and garnish with sesame seeds and green onions.
Notes
Cook the noodles al dente. They will continue to soak up some of the teriyaki sauce once you add them to the stir fry.
Don't overcook the veggies, they taste best if they are still a little crunchy, you don't want soggy vegetables.