Overview
Mongolian beef is a beloved Chinese-American takeout classic featuring tender beef in a rich, slightly sweet soy-ginger sauce loaded with green onions. Sous vide guarantees perfectly tender meat every time, while a quick stir-fry adds the characteristic glossy sauce coating and aromatic finish.
Core Time & Temperature
| Doneness | Temperature | Time | Max Time |
|---|---|---|---|
| Tender | 130°–135°F | 2–3 h | 6 h |
| Firmer | 140°–145°F | 2–3 h | 6 h |
Cooking time depends on thickness, not weight. Flank steak slices cook quickly.
Food Safety Notes
Beef should reach at least 130°F / 54°C for medium-rare. Cooking at 130°–145°F for 1–3 h ensures pasteurization. The quick stir-fry finish adds additional heat. Always sear the exterior in a ripping-hot pan or grill to eliminate surface pathogens. Serve immediately.
See our food safety guide.
Texture Profiles
- 130°–135°FTender
- Incredibly tender beef with a slight pink center, coated in glossy sweet-savory sauce. This is the perfect texture for restaurant-style Mongolian beef.
- 140°–145°FFirmer
- Fully cooked beef with firmer texture, still tender thanks to sous vide. The sauce coating keeps it moist and flavorful.
Prep & Bagging
- Slice flank steak against the grain into 1/4-inch strips (Against the grain is essential for tenderness)
- Toss beef strips with cornstarch until evenly coated (This creates velvety texture and helps sauce adhere)
- Place coated beef in vacuum bag or zip-top bag (Can layer flat for even cooking)
- Vacuum seal or use water displacement method
- Ensure bag is fully submerged in water bath
Finishing & Crisping
- Prepare sauce while beef cooks
- Remove beef from bag and pat dry
- Heat wok or large skillet over highest heat
- Add oil, then garlic and ginger
- Add beef and stir-fry 1–2 min
- Pour in sauce and bring to boil
- Cook 2–3 min until sauce thickens and coats beef
- Add green onions and sesame oil, toss 30 sec
- Transfer to serving platter, sprinkle with sesame seeds
- Serve immediately over steamed rice