Pull frozen veggies out of the freezer OR slice/dice fresh veg into desired shape and size.
Cut chicken into bite-sized chunks.
Slice mushrooms and onion to desired thickness if using.
Make Teriyaki Sauce:
Combine 1 cup water, soy sauce, brown sugar, honey, ginger, and garlic in a saucepan over medium heat.
Cook and stir, about 1 minute.
Mix cornstarch and ¼ cold water together in a cup until dissolved. Add to the saucepan while whisking.
Cook and stir sauce until thickened, 5 to 8 minutes. Set aside either on lowest heat possible or cover to keep warm.
Make Stir Fry:
Set a pot of water to boil for noodles.
Add oil/fat to cast iron pan and cook chicken over medium heat until cooked through. Remove to a plate and cover.
Add a generous amount more fat of choice and begin to stir fry veggies. If you are doing fresh, start with the sturdiest first, such as carrots. Save mushrooms for last. The key is to try and get all veg done to your liking at the same time!
Add half the teriyaki sauce, and turn heat to medium-low.
Return chicken to the pan with the veggies and stir to combine. Reduce heat as low as you can so it doesn't burn, and cover.
Cook noodles according to package directions.
In a large bowl, add cooked noodles, cooked stir fry, and top with remaining teriyaki sauce.
Dish up and let people add toppings as desired.
Notes
Use tamari sauce instead of soy sauce and brown rice noodles to make the dish gluten-free.
Feel free to use dark meat chicken or venison, beef, etc. Just cut to bite-sized and cook meat first before anything else is cooking.