Step 1: Prep the Beef

1. Place the thinly sliced flank steak in a large zip-top bag.
2. Add ¼ cup cornstarch, seal the bag, and shake well to evenly coat the beef. Set aside while you prepare the sauce.

Beginner Tip: Coating the beef in cornstarch helps create a light crust when cooked, allowing the sauce to stick better and giving the beef a velvety texture.

Step 2: Make the Sauce

1. In a medium saucepan, heat 1 tablespoon of olive oil and 1 tablespoon of sesame oil over medium-high heat.
2. Add the minced garlic and ginger. Sauté for about 1 minute until fragrant, being careful not to burn the garlic.
3. Add the soy sauce, water, and brown sugar, stirring until the sugar dissolves.
4. Bring the sauce to a boil for 2 to 3 minutes, then reduce the heat and let it simmer for 5 minutes until slightly thickened.

Beginner Tip: Keep the heat at medium to avoid burning the garlic, which can make the sauce taste bitter.

Step 3: Cook the Beef

1. In a large skillet or wok, heat the remaining 2 tablespoons of olive oil and 1 tablespoon of sesame oil over medium-high heat.
2. Add the cornstarch-coated beef and cook for 5 to 7 minutes, flipping the pieces occasionally to ensure even browning.
3. Once the beef is cooked through and browned, add the broccoli.

Beginner Tip: To check if the beef is done, slice into a piece. It should be brown throughout with no pink remaining.

Step 4: Combine Everything

1. Pour the prepared sauce over the beef and broccoli. The sauce will bubble up, so stir quickly to coat everything evenly.
2. Let the mixture simmer for 3 to 5 minutes, until the broccoli is cooked to your preferred tenderness.
3. If the sauce is too thin, mix 1 tablespoon cornstarch with 1 tablespoon water to create a slurry, then add it to the skillet. Stir for 1 minute until thickened.

Step 5: Finish and Serve

1. Turn off the heat and stir in the green onions.
2. Optionally, sprinkle with red pepper flakes for extra flavor and sesame seeds for garnish.
3. Serve immediately over steamed rice or noodles.