Mongolian Beef Stir Fry

Overview

This takeout-style Mongolian beef relies on a simple trick: coating thin-sliced flank steak in cornstarch before searing. The starch creates a lightly crispy exterior that grabs onto the sweet-savory sauce, giving you that glossy, sticky coating that makes restaurant versions so addictive. Twenty-five minutes, start to finish.

Steps

1. Prep the beef

Toss the sliced flank steak with cornstarch until every piece is evenly coated. Let sit for 10 minutes — this gives the cornstarch time to adhere and hydrate, which is key for achieving that classic crispy texture.

For easier thin slicing, partially freeze the steak for about 20 minutes first.

Cornstarch resting — 10 min

2. Mix the sauce

In a small bowl, stir together the soy sauce, brown sugar, and water until the sugar dissolves. Set aside.

3. Sear the beef

Heat the vegetable oil in a wok or large skillet over medium-high heat until shimmering. Add the beef in batches — do not crowd the pan. Cook each batch 2-3 minutes until browned and slightly crispy on the edges. Remove and set aside.

Technique: The Maillard ReactionThe chemical reaction behind browning — and why it makes food taste so good.

Searing per batch — 3 min

4. Build the flavor

Drain most of the oil from the pan, leaving about 1 tablespoon. Add the minced garlic and grated ginger. Cook for about 30 seconds until fragrant — don’t let it burn.

5. Combine everything

Pour in the sauce and bring to a simmer. Cook 2-3 minutes until slightly thickened. Add the seared beef back to the pan. Toss in the green onion pieces. Cook another 1-2 minutes, tossing constantly, until every piece is glossy and coated.

Sauce reducing — 3 min

6. Serve

Plate over steamed white or jasmine rice. Garnish with sesame seeds if desired.

Notes

• Slice thin, against the grain: This is the biggest factor in tender results. Partially freezing the steak for 20 minutes makes this much easier.
• Don’t skip the cornstarch: It serves double duty — creating the crispy exterior on the beef and thickening the sauce as it reduces.
• High heat is essential: You want a quick sear, not steaming. If the beef is releasing liquid and sitting in it, your pan isn’t hot enough or it’s overcrowded.
• Want it spicy: Add a pinch of red pepper flakes with the garlic and ginger.
• Bulk it out: Broccoli florets or sliced bell peppers can be stir-fried separately and added at the end for a more complete meal.