Instructions

• Place 1 ½–2 pounds flank steak (sliced into ¼-inch strips) and ⅓ cup cornstarch into a large zip-top bag. Seal the bag and shake vigorously until all strips are evenly coated. Set the coated beef aside for about 15 minutes.
• While the beef rests, whisk together ½ cup low-sodium soy sauce, ⅓ cup light brown sugar (lightly packed), ⅓ cup water, and 1 tablespoon rice vinegar in a medium bowl; set the sauce aside.
• Heat a large 14-inch (or similarly large) skillet over medium-high heat until hot. Add 1 tablespoon vegetable oil and swirl to coat the pan.
• Add half of the coated beef in a single layer (do not overcrowd). Cook undisturbed 3–4 minutes, flip, and cook another 3–4 minutes until browned. Transfer the cooked beef to a plate.
• Add the remaining 1 tablespoon vegetable oil to the skillet, heat, then add the remaining beef in a single layer. Cook undisturbed 3–4 minutes, flip, and cook another 3–4 minutes until browned. Transfer the beef to the plate with the first batch.
• Reduce heat to medium. Add ½ teaspoon sesame oil to the skillet, then add 2 teaspoons minced garlic and 1 teaspoon minced fresh ginger. Cook, stirring, for about 1 minute until fragrant.
• Pour the reserved soy sauce mixture into the skillet, scraping up any browned bits from the bottom. Bring to a simmer and cook 2–3 minutes, stirring, until the brown sugar is dissolved.
• In a small bowl, combine 1 tablespoon cornstarch and 2 tablespoons water to make a slurry. Stir the slurry into the simmering sauce and continue to simmer over medium-low heat for 1–2 minutes, stirring, until the sauce thickens.
• Return the cooked beef to the skillet and stir to coat in the sauce. Cook 1–2 minutes more until the beef is heated through. Serve immediately over rice.