Let’s get cooking! Follow these simple steps, and you’ll have Beef Lo Mein in no time.

1. Prep the Ingredients: Start by thinly slicing your flank steak against the grain. This helps make the beef tender and easy to chew. Then, chop your vegetables—carrots, bell peppers, and green onions—into thin strips. If you’re adding any additional vegetables like bok choy or mushrooms, slice them too.
2. Cook the Noodles: Bring a large pot of salted water to a boil. Cook the lo mein noodles according to the package instructions (usually about 4-5 minutes). Once they’re done, drain and set aside. Be sure to toss them with a little sesame oil to prevent them from sticking.
3. Make the Sauce: In a small bowl, whisk together the soy sauce, hoisin sauce, sesame oil, oyster sauce, rice vinegar, and brown sugar. In a separate bowl, mix the cornstarch with a tablespoon of water to create a slurry. This will help thicken the sauce as it cooks.
4. Cook the Beef: Heat 1 tablespoon of vegetable oil in a large skillet or wok over medium-high heat. Once hot, add the thinly sliced beef. Let it sear for 2-3 minutes without moving it around too much, so it gets a nice golden-brown color. Stir occasionally until the beef is cooked through, about 5-6 minutes total. Remove the beef from the skillet and set it aside.
5. Stir-Fry the Vegetables: In the same skillet, add the remaining tablespoon of vegetable oil. Toss in the garlic and let it cook for about 30 seconds, or until fragrant. Then, add the carrots, bell peppers, and any other veggies you’re using. Stir-fry for about 3-4 minutes until they’re tender but still crisp.
6. Combine Everything: Add the cooked beef back into the skillet along with the noodles. Pour in the sauce, followed by the cornstarch slurry. Toss everything together to coat the noodles, beef, and veggies in the sauce. Continue cooking for another 2-3 minutes, or until the sauce has thickened and everything is heated through.
7. Final Touches: Sprinkle the sliced green onions over the top and give everything one final toss. The dish should be glossy and slightly sticky, with all the noodles perfectly coated in the sauce.