Slice beef into thin strips cross grain. Bring beef, soy sauce, corn starch and vegetable oil into a medium bowl. Stir to coat beef in seasonings. Marinade for 30 minutes.
While waiting on beef to marinade, bring water in a medium pot to boil and cook ramen noodles based on package instructions. Drain water and set aside. Rinse with cold water if they stick together.
Prepare Mongolian stir fry sauce by combining all ingredients in a bowl. Whisk to combine.
Heat a large skillet or wok with cooking oil under high/medium high heat. Once heated, add beef. Stir continuously for a few minutes until beef is no longer pink - this should take 1-2 minutes under high heat. Remove beef promptly and set aside - do not overcook beef.
Add more cooking oil if needed. Add snow peas and carrots. Stir continuously until they are cooked (brighter colors but still crunchy). This should take a couple of minutes.
Add stir fry sauce, noodles and beef to skillet. Toss to combine so noodles are coated in sauce. Remove from heat promptly.
Garnish with green onions. Serve and enjoy!