2 lbs beef flank steak, cut lengthwise in half, then across grain into 1/2 inch wide slices
1/2 C low sodium soy sauce or GF tamari sauce
1/2 C beef broth
1/2 C packed dark brown sugar
2 T unseasoned rice vinegar
6 medium garlic cloves, minced (2 T)
1 T minced peeled fresh ginger
3 T water
2 T cornstarch
Medium scallions, trimmed and cut into 1-inch sections, for garnishing
Stir the beef, soy sauce, broth, brown sugar, vinegar, garlic and ginger in a 5 or 6 qt Instant Pot until the beef is evenly coated in the sauce and the brown sugar is dissolved. Lock the lid on the pot.
Set pot for: Pressure Cook or Manual, Level High, Valve closed, Set time for 3 minutes with the Keep Warm setting off. Start
OR
Slow Cook Setting: Set pot for: Slow Cook. High, Valve opened, 3 hours with the Keep Warm setting off. Start.
When the pot has finished cooking under pressure, turn it off and let its pressure return to normal naturally, about 20 minutes. Whichever cooking method you've used, unlatch the lid and open the cooker. Whisk the water and cornstarch in a small bowl until smooth.
In all models set pot for: Saute. Medium, Normal or Custom 300, set time for 5 minutes. Start
As the sauce comes to a simmer, stir in the cornstarch slurry. Cook, stirring constantly, until somewhat thickened, less than 1 minute. Turn off the heat and use hot pads or silicone baking mitts to transfer the (hot!) insert to a nearby wire rack (to stop the cooking. Cool for 2 to 3 minutes, then garnish the servings with sliced scallions.
Serve over cooked long-grain white rice, particularly jasmine rice.