Place beef tenderloin strips in a medium bowl. Add 1 tablespoon Bibigo Korean BBQ Sauce & Marinade Original (add more to taste) and gently mix the sauce into the meat. Cover the bowl and set aside.
Whisk all sauce ingredients in a small bowl until sugar is dissolved.
Bring a large pot of lightly salted water to a boil and cook the pasta according to package directions, about 6-7 minutes. Rinse the pasta under cold water and drain. In a large mixing bowl, stir in 2 tablespoons of the prepared sauce.
Stir-fry the glasnoodle over medium heat for 2 minutes until translucent. Return to the mixing bowl.
Add 1 teaspoon oil to pan and sauté onion over medium heat for 1-2 minutes, stirring, until translucent. Transfer to the mixing bowl. Add another teaspoon of oil and stir-fry the carrots and bell bell pepper for 1-2 minutes, until lightly browned. Add to the mixing bowl. Do not overcook. The vegetables should be crisp.
Add 1 teaspoon of oil and stir-fry the marinated beef tenderloin strips and mushrooms for 2-3 minutes until browned. Add to the mixing bowl.
Add the spinach and remaining sauce to the bowl. Toss well by hand to coat evenly and serve.