Mix beef marinade and toss with beef strips; set aside. Bring a large pot of water to a boil. Add the noodles and cook until just tender, about 4 minutes (if using gluten-free noodles, follow package al dente cooking directions). Drain well and transfer to a large bowl. Toss with the sesame oil to coat lightly and set aside.
In a small bowl, combine the oyster sauce, soy sauce, fish sauce, cornstarch, and pepper; stir to dissolve the cornstarch.
In a large skillet or wok, add beef to the skillet with 2 tablespoons coconut oil over med-high heat and cook until lightly browned. Remove beef from skillet and set aside.
In the same skillet, heat the remaining 1 tablespoon of coconut oil over medium-high heat. Add the garlic, ginger, zucchini, and carrots and cook for 2-3 minutes or until garlic and ginger are fragrant and vegetables have softened.
Add the pepper flakes, green onions, mushrooms, and snow peas, and cook, stirring, for about 2 minutes. Return beef to the skillet with vegetables.
Reduce heat to medium, add the noodles and sauce, gently tossing the sauce with the noodles and vegetables until well coated; cook until the sauce is bubbly and thickened. Serve immediately.
To make this dish gluten-free, look for the following:Panda Brand (Green Label) Oyster Flavored Sauce or Wok Mei All Natural Oyster Sauce Tamari Soy Sauce brands like San-J Gluten-Free Asian Noodles or Ancient Harvest Quinoa pasta Rachael Ray Beef Stock-in-a-Box (recommended for flavor by Cooks Illustrated) or Imagine Organic Beef Flavored Broth