Clean & prep the meat beforehand. Cut the steak into strips by slicing very thinly against the grain into about 1 to 1 ½ inch strips.
Marinate the steak: Add the steak to a bowl and coat with the sherry cooking wine, soy sauce, & cornstarch. Mix everything together & marinate the meat for at least 5 to 10 minutes.
Next, prepare the Mongolian beef sauce. In a large bowl add the hot water, brown sugar, soy sauce, and sherry cooking wine. Mix until the sugar dissolves, then set the sauce to the side.
Over medium-high to high heat, add 1 Tbsp of olive oil to a wok/skillet. Once the oil is hot add the steak strips and sear until the meat is browned and crispy (About 2 to 4 minutes). You may have to brown the meat in batches. Remove the meat from the skillet and set aside. scrap any meat drippings stuck to the skillet.
Next, add the sliced white onion and sauté for a minute or two. Add the ginger paste and fresh minced garlic, sauté for a few seconds or until fragrant.
Mix everything together and pour the Mongolian beef sauce into the wok as well as the cornstarch slurry.
Stir everything together and allow the sauce to simmer for 2 minutes.
Add the cooked steak strips & mix into the sauce. Simmer for 2 minutes or until the sauce thickens up.
Toss the sliced green onions into the wok. Stir everything together and Cook a few seconds. Optional: you can add a pinch of crushed red pepper.
The sauce should thicken up but keep an eye on the sauce to prevent burning.
Tip: Most recipes call for the sauce to thicken up so much that there is no liquid in the pan. But I like to have a little bit of sauce/liquid to pour over my rice. It this is completely optional.
Serve over rice. Enjoy!