Mongolian Beef Recipe

Slice steak

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

Season the sliced beef lightly with 1/2 tsp salt and 1/4 tsp black pepper and toss to distribute.

Place 1 cup cornstarch in a shallow bowl or plate. Dredge each beef slice in cornstarch, shaking off excess so each piece has a light, even coating.

Heat 1 cup vegetable oil in a heavy skillet or wok over medium-high heat until it reaches 350°F (or is shimmering). Working in batches to avoid overcrowding, fry the cornstarch-coated beef slices 45–90 seconds per side until crisp and lightly golden. Use a slotted spoon to transfer cooked beef to a paper towel-lined plate. Keep warm and repeat until all beef is cooked.

In a small bowl, whisk together 1/2 cup low-sodium soy sauce, 1/4 cup water, 1/2 cup packed dark brown sugar, 1 tbsp hoisin (if using), 1 tbsp rice vinegar, and 1 tsp sesame oil until the sugar is mostly dissolved.

In a separate small cup, mix 1 tbsp cornstarch with 1–2 tbsp cold water to make a smooth slurry; set aside.

After removing the beef, discard all but 1–2 tablespoons of oil from the skillet, leaving browned bits. Return skillet to medium heat and add the minced ginger and minced garlic. Sauté 30–45 seconds until fragrant (do not burn). Add 1/4 tsp red pepper flakes if using and sauté 10 more seconds.

Pour the prepared soy-sugar sauce into the skillet, scraping up any browned bits from the bottom. Bring the sauce to a gentle simmer, stirring to combine.

Stir the cornstarch slurry again and slowly whisk it into the simmering sauce. Continue to simmer 1–2 minutes until the sauce thickens to a glossy, clingy consistency that will coat the beef.

Return the fried beef to the skillet and toss quickly to coat every piece in the sauce. Cook together 1–2 minutes just to reheat the beef and allow the sauce to adhere; avoid overcooking to keep beef tender.

Add most of the sliced green onions (reserve a few for garnish) and toss to combine. Remove skillet from heat. Taste and adjust: add a pinch of salt or a splash of soy if you want it saltier, or a pinch more sugar if you prefer sweeter.

Transfer the Mongolian beef to a serving platter, sprinkle with toasted sesame seeds and remaining green onions. Serve immediately over steamed rice.