Mongolian Beef and Noodles With Flank Steak

This Mongolian beef and noodles recipe takes about 35 minutes from cutting board to bowl. Flank steak is sliced thin across the grain, tossed in cornstarch and seared hot in batches, then simmered for a minute in a glossy sauce of soy, brown sugar, ginger and garlic. Lo mein or egg noodles go into the same pan at the end and soak up the rest of the sauce.

Flank suits it well. It is lean and full of beef flavor, its grain runs in long, obvious lines, and it cuts into neat, even strips that brown quickly and stay tender, as long as you slice them across the grain and do not crowd the pan.

At a glance: serves 4. Prep 20 minutes, cook about 15 minutes, total 35 minutes.

Talking about what he likes to cook, Gray Shipley, who runs the farm, said:

“I like taking out maybe some skirt steak, some fajita meat, and, you know, making some tacos, making some fajitas, getting something that you can just kind of chop up and mix up whatever.”

Gray Shipley

He was talking about skirt steak and fajitas, not this dish, and he did not mention flank. The idea is the same one, though: a thin, beefy steak that you slice up and toss with everything else in the pan. Flank does that job well here, and because it is thicker and more even than skirt, it is easier to cut into strips that all cook at the same speed.

Ingredients

• 1 flank steak, 1 to 1 3/4 pounds, thawed
• 3 tablespoons cornstarch
• 8 ounces lo mein noodles or dried egg noodles
• 1/2 cup low-sodium soy sauce
• 1/2 cup water
• 1/3 cup packed dark brown sugar
• 1 tablespoon finely grated fresh ginger
• 4 cloves garlic, finely minced
• 1 teaspoon toasted sesame oil
• 1/4 teaspoon red pepper flakes (optional)
• 3 to 4 tablespoons peanut, canola or other neutral oil, divided
• 5 scallions, white and light green parts cut into 1-inch pieces, dark green tops thinly sliced
• 1 teaspoon toasted sesame seeds, to serve (optional)

Instructions

1. If you have time, put the steak in the freezer for 20 minutes so it firms up and slices more easily. Cut it lengthwise, with the grain, into strips about 2 inches wide. Turn each strip and slice it across the grain into pieces about 1/4 inch thick.
2. Toss the beef with the cornstarch in a bowl until every piece is lightly coated. Let it sit while you make the sauce and cook the noodles.
3. Whisk the soy sauce, water, brown sugar, sesame oil and red pepper flakes in a measuring cup until the sugar dissolves. Set it by the stove with the ginger, garlic and scallions.
4. Cook the noodles in a large pot of boiling water according to the package directions until just tender. Drain, rinse briefly under warm water so they do not stick together, and set aside.
5. Heat 1 tablespoon of the neutral oil in a large skillet or wok over high heat until it shimmers. Shake the excess cornstarch off a third of the beef and lay it in the pan in a single layer. Cook without moving it for 1 to 2 minutes, until browned underneath, then turn and cook 1 minute more. Move it to a plate and repeat with the rest of the beef, adding oil as needed.
6. Turn the heat to medium. If the pan is dry, add a little more oil. Add the ginger, garlic and white scallion pieces and stir for about 30 seconds, until fragrant. Pour in the sauce and scrape up the browned bits. Simmer for 2 to 3 minutes, until it thickens slightly and turns glossy.
7. Return the beef and any juices to the pan and simmer for 1 to 2 minutes, turning, until the sauce coats every piece and the beef is cooked through. Add the noodles and toss with tongs for about a minute, until hot and evenly coated. Scatter with the sliced scallion tops and sesame seeds and serve.

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Is Mongolian beef easy to make?

Yes. It is one of the easiest takeout-style dishes to make at home, and most of the work is slicing. There is no marinade to plan for and no wok required: a 12-inch skillet does the job. The only real rules are to cook the beef in batches, so each piece browns instead of steaming, and to mix the sauce before the pan gets hot, because everything after that moves quickly.

The cornstarch does two jobs. It gives the strips a thin, lightly crisp coat in the hot oil, and whatever clings to them thickens the sauce when the beef goes back in. If the sauce gets too thick, loosen it with a splash of water. If it looks thin, let it simmer a minute longer before the noodles go in.

Slicing flank steak for Mongolian beef

Flank's grain runs the length of the steak. Cutting it into wide strips along the grain first, and then slicing each strip across the grain, gives you short, tender pieces instead of long, chewy ones. A firm, partly frozen steak is much easier to slice thin, which is why the 20 minutes in the freezer helps, and a sharp knife matters more than an expensive one. For more on which cuts suit a hot pan and how to slice each, see Best Beef Cuts for Stir-Fry, and How to Slice Them.

Mongolian beef with noodles or rice

Here the noodles are part of the dish, not a side, so the sauce is more generous than you would make for rice. Lo mein noodles are the usual choice; dried egg noodles or even spaghetti work too. To serve it over rice, leave out the noodles and simmer the sauce a minute longer so it clings to the beef.

Making it ahead for the freezer or slow cooker

You can freeze the raw sliced beef in its sauce for a later night. Put the uncoated strips in a freezer bag with the mixed sauce, ginger and garlic, press out the air, seal, label and freeze it flat. Thaw it overnight in the refrigerator, never on the counter, and thaw it fully before cooking it any way, including in a slow cooker. On the stove, lift the beef out of the sauce, pat it dry, toss it with the cornstarch and pick up the recipe at step 5. In a slow cooker, cook the thawed beef and sauce on low for about 4 hours, stir in 2 tablespoons of cornstarch mixed with 2 tablespoons of water for the last 15 minutes to thicken it, and cook the noodles separately. The beef will be softer and less browned than the skillet version.

Food safety

USDA FSIS lists 145 degrees F, followed by a rest of at least 3 minutes, as the safe minimum internal temperature for beef steaks and other whole cuts. Thin strips are hard to probe, but they cook through quickly, and the final simmer in the sauce finishes them. If you want to be sure, check the thickest piece with an instant-read thermometer. Keep the raw beef, and the board and knife you sliced it with, away from food that will not be cooked. Refrigerate leftovers promptly and reheat them to 165 degrees F. See the FSIS Safe Minimum Internal Temperature Chart.