Mongolian Beef Or Tofu Recipe

Prepare protein

If using beef: partially freeze flank steak for 20–30 minutes to firm it, then slice very thinly across the grain into 1/8–1/4" strips. Place sliced beef in a bowl. If using tofu: press extra-firm tofu for 15–30 minutes to remove excess water, then slice into 1/4" strips.

In the bowl with the beef or tofu, add 1 tablespoon soy sauce and 1 tablespoon cornstarch. For beef only, if desired for extra tenderness, add 1/2 teaspoon baking soda and gently massage for 1 minute. Let rest 10–15 minutes while you prepare the sauce and aromatics (this helps the cornstarch adhere and the baking soda tenderize).

Mix sauce

In a medium bowl or measuring cup combine 1/2 cup low-sodium soy sauce, 1/4 cup water, 1/4 cup packed brown sugar, 1 teaspoon hoisin (optional), 1 teaspoon oyster sauce (omit for vegetarian/vegan), 1 teaspoon rice vinegar, and 1/2 teaspoon sesame oil. Whisk until the sugar dissolves.

In a small bowl whisk 2 teaspoons cornstarch with a tablespoon or two of water to make a smooth slurry; set aside. You will add the slurry later to thicken the sauce.

Cook protein

Heat a wok or large skillet over medium-high to high heat until very hot. Add 2 tablespoons vegetable oil and swirl. If cooking beef: add half the beef in a single layer (do not crowd) and sear 30–60 seconds per side until browned but not fully cooked through; remove to a plate and repeat with remaining beef, using the last tablespoon oil if needed. If cooking tofu: add tofu strips in a single layer and pan-fry until golden and crisp on both sides, 2–3 minutes per side; work in batches to avoid overcrowding, then set aside.

Return the wok to medium heat and add a tablespoon oil if the pan is dry. Add the white parts of the sliced scallions, the minced garlic, minced ginger, and red pepper flakes (if using). Stir-fry 20–30 seconds until fragrant but not browned.

If using bell pepper, add the thinly sliced red bell pepper now and stir-fry for 30–45 seconds until slightly softened but still crisp.

Make sauce and finish

Pour the prepared soy/brown sugar sauce mixture into the wok with the aromatics. Bring to a simmer, scraping up any browned bits from the bottom of the pan. Taste and adjust: add a bit more sugar if you want sweeter, or a splash of water if too salty.

Stir the cornstarch slurry again (it may have settled) and slowly pour into the simmering sauce while stirring. Simmer 30–60 seconds until the sauce thickens to a glossy, clingy consistency.

Return the seared beef or crispy tofu to the wok and toss to coat in the sauce. Stir-fry for another 1–2 minutes so the beef finishes cooking and the sauce adheres, or to heat the tofu through. Add the green parts of the scallions at the last 30 seconds and toss.

Remove from heat. Drizzle 1/2 teaspoon toasted sesame oil over (optional) and toss gently. Sprinkle toasted sesame seeds and additional sliced scallions to garnish.

Serve immediately over steamed rice or noodles.