Thinly cut the flank steak against the grain, and then dice. Put the steak in a bowl.
1 pound flank steak
Season flank steak with salt and pepper to taste, and coat with the cornstarch. Mix until well combined.
salt, black pepper, ¼ cup cornstarch
Mince the ginger and garlic.
3 garlic cloves, 1 inch ginger
Add the vegetable oil to the bottom of the slow cooker, and then add the steak.
2 tablespoons vegetable oil
Then add the garlic, ginger, brown sugar, sesame oil, soy sauce and water. Mix until well combined.
½ cup lower sodium soy sauce, ⅓ cup brown sugar, 1 tablespoon sesame oil, ¼ cup water
Cook on low for 4-5 hours or on high for 2.5 hours. Stir when done cooking.
Slice the scallion. Garnish the Mongolian beef with the diced scallion and sesame seeds and serve over rice.
1 scallion, 1 tablespoon sesame seeds
Notes
Sirloin is another good cut of beef to use in this recipe, if desired.
To streamline prep, instead of mincing fresh ginger and garlic, substitute about 1 tablespoon of ginger paste and 1 ½ teaspoons jarred minced garlic.
This dish is even better with some vegetables added in, such as onions, bell peppers, or green onions. Add them in the last hour of cooking to prevent them from becoming too mushy.
If the sauce is too thin at the end of the cooking time, you can thicken it by making a cornstarch slurry (cornstarch mixed with water) and adding it to the slow cooker. Cook for an additional 15-30 minutes until the sauce has thickened.