In a bowl, add the soy sauce, vinegar, brown sugar, cornstarch, ginger, and scallions. Whisk to combine.
½ cup low-sodium soy sauce, 3 Tablespoons rice wine vinegar, 2 Tablespoons brown sugar, 2 Tablespoons cornstarch, 1 Tablespoon fresh ginger, 3 whole scallions
Add the steak to a bowl or sealable bag, pour the sauce on top, and toss to combine. Set aside.
1 ½ pounds flank steak
Heat the oil in a large non-stick skillet or wok. Add the snow peas, stirring for 45 seconds. Remove from the skillet, and set aside.
2 Tablespoons olive oil, 10 ounces fresh snow peas
Allow the skillet to become very hot again. Using tongs, add half the steak to the skillet in a single layer.
Let the steak sit for 1 minute or until seared. Then, flip it over, and continue to cook for 30 seconds. Transfer it to a plate, and repeat the process with the remaining steak.
Add all the cooked steak and snow peas back to the skillet, and stir over high heat for 30 seconds.
Turn off the heat, and let the mixture sit until thickened.
Serve immediately over white rice topped with green onions, crushed peanuts, and crushed red pepper flakes, if desired.
Optional: white rice for serving, Optional: green onions
Store in an airtight container in the fridge for up to 5 days.