Mongolian Beef, Spicy Recipe

Slice beef

Trim fat from the flank steak and slice thinly across the grain into 1/8 to 1/4-inch slices. Partially freeze steak for 20–30 minutes beforehand to make slicing easier.

Marinate

In a bowl combine 2 tablespoons soy sauce and 1 egg white. Add the sliced beef and toss to coat. Let sit 10 minutes to slightly tenderize.

Coat with cornstarch

Place 1/2 cup cornstarch in a shallow dish. Working in batches if needed, dredge the marinated beef pieces in the cornstarch, shaking off excess so each piece has a light, even coating.

Fry beef

Heat 1/2 cup vegetable oil in a large skillet or wok over medium-high heat until shimmering (about 350°F/175°C). Fry the coated beef in batches so pieces are in a single layer and not crowded, about 2 minutes per side, until crisp and browned. Transfer to a paper-towel-lined plate to drain. Reserve oil in the pan for the sauce (leave about 1 tablespoon) or discard excess leaving 1 tablespoon.

Prepare sauce mixture

In a bowl combine 4 tablespoons soy sauce, 1 tablespoon dark soy sauce, 3 tablespoons brown sugar, 1 tablespoon rice vinegar, 1/4 cup water, 1 teaspoon sesame oil, 1 teaspoon crushed red pepper flakes, 1 tablespoon minced ginger, 2 teaspoons minced garlic, and 1 teaspoon chili paste if using. Stir until sugar begins to dissolve.

Make slurry

In a small cup, mix 1 teaspoon cornstarch with 1 tablespoon cold water to form a thin slurry and set aside.

Cook aromatics

Heat the reserved 1 tablespoon oil in the same skillet or wok over medium-high heat. Add minced ginger and garlic and stir-fry for about 20–30 seconds until fragrant but not browned. Add crushed red pepper flakes and optional sliced chilies and stir 10 seconds.

Add sauce and thicken

Pour the prepared sauce mixture into the pan, bring to a simmer, and let it cook 1–2 minutes to meld flavors. Stir the cornstarch slurry once more and slowly add to the simmering sauce, stirring constantly, until the sauce thickens to a glossy coating consistency, about 30–60 seconds. Taste and adjust heat or sweetness as desired.

Combine with beef

Return the fried beef to the pan and toss quickly to coat each piece evenly with the spicy Mongolian sauce. Cook together 1–2 minutes until beef is heated through and sauce clings to the meat.

Stir in the sliced green onions, reserving a few for garnish, and toss once just to wilt slightly (about 30 seconds). Transfer the Mongolian beef to a serving platter, sprinkle with toasted sesame seeds and the remaining green onions. Serve immediately over steamed white rice or fried rice.