Combine marinade ingredients in bowl and add flank steak. Set aside 15 minutes.
Heat 1 Tbsp vegetable oil in large skillet over MED HIGH heat. Remove excess marinade from steak and cook in a single layer, for 2-3 minutes, stirring to cook both sides. Depending on the size of your pan, you may need to do this in batches. Remove steak to plate.
Heat remaining 1 Tbsp vegetable oil, then add peas, carrots and green onion and cook stirring often, 2-3 minutes.
Whisk together broth, soy sauce, honey/brown sugar, rice vinegar, garlic, sesame oil, fresh ginger, cornstarch, and red pepper flakes. Add steak and sauce to skillet, stirring to combine. Sauce will thicken.
Stir in cooked ramen noodles if using, and serve!
