Start by preparing your beef. Place it in the freezer for about 30 minutes if it is not partially frozen. This helps make slicing thin pieces easier. Use a sharp knife to slice the beef against the grain into 1/8 to 1/4 inch strips. Thin slices cook quickly and soak up the marinade beautifully.

Make the marinade by combining soy sauce, brown sugar, sesame oil, minced garlic, grated ginger, and black pepper in a large mixing bowl. Whisk everything together until the sugar is mostly dissolved. This mixture forms the base of the flavorful sauce that will coat every bite.

Toss the beef slices into the marinade, making sure each piece is well coated. Add sliced onions, carrots, and green onions into the bowl for extra flavor and crunch. Cover the bowl with plastic wrap and refrigerate for at least 30 minutes, ideally one to two hours. For maximum flavor, you can marinate overnight.

Heat a non-stick skillet or grill pan over medium-high heat. Once hot, add a small drizzle of oil to prevent sticking. Add the marinated beef in a single layer, being careful not to overcrowd the pan. Cooking in batches is okay if needed.

Cook the beef for 2 to 3 minutes on each side until nicely caramelized. The high heat helps the sugar in the marinade create a beautiful, slightly crisp edge. Remove cooked beef from the pan and repeat with the remaining slices.

Serve immediately with steamed rice, lettuce leaves for wraps, or a side of sautéed vegetables. Garnish with sesame seeds and extra green onions for that restaurant-style presentation. Enjoy the dish warm, and feel free to drizzle a little extra marinade sauce over the top for added flavor.