Step 1: Begin by slicing your flank steak against the grain into 1/4-inch thick strips.
Step 2: In a mixing bowl, toss the sliced beef with 1/4 cup of cornstarch until evenly coated.
Step 3: In another bowl, whisk together the low-sodium soy sauce, light brown sugar, water, rice vinegar, minced garlic, and minced ginger.
Step 4: In a large skillet or wok, heat 2 tablespoons of vegetable oil over medium-high heat. Add the beef strips and cook for 2-3 minutes without stirring.
Step 5: After searing, stir the beef until browned and cooked through, then remove from the skillet.
Step 6: In the same skillet, add the teriyaki sauce mixture and bring it to a gentle boil.
Step 7: Add the cornstarch slurry while stirring continuously to thicken the sauce.
Step 8: Return the cooked beef to the skillet and toss it in the thickened sauce until well coated.
Step 9: Serve your Easy, Tender Beef Teriyaki over steamed rice, noodles, or with fresh vegetables.