In a bowl, whisk together soy sauce, water, cornstarch, ginger, garlic, and brown sugar until completely combined. Set aside.
½ cup soy sauce, ½ cup cold water, ¼ cup cornstarch, ½ teaspoon minced fresh ginger, 1 tablespoon minced garlic, ¼ cup brown sugar
Heat 2 tablespoons of canola oil in a large skillet over high heat. Add the broccoli and stir for about 1 minute. Remove to a plate and set aside.
16 ounces broccoli florets
Add meat to the skillet in a single layer (still over high heat) and cook for about 1 minute – do not stir or move the meat while it is browning. Flip the meat, cook on the other side for about 30 more seconds, and then remove to the plate with the broccoli.
1 lb. flank steak
Pour the sauce into the skillet and bring to a boil, then allow to simmer while whisking until the sauce thickens (about 1-2 minutes). If the sauce gets too thick, just add additional water until it reaches desired consistency. Add broccoli and beef back to the skillet and stir to coat with the sauce. Serve over rice.