First, I freeze the steak for about 30 minutes to make it easier to slice thinly against the grain. Thin strips, about 1/8″ to 1/4″, cook quickly and stay tender.
Mix soy sauce, brown sugar, minced garlic, ginger, sesame oil, water, and cornstarch. I simmer it for a few minutes to let the flavors meld and thicken slightly.
I sauté fresh broccoli in a hot skillet with a splash of water until bright green and tender-crisp, then remove it to avoid overcooking.
Next, I sear the beef strips in the same skillet on high heat. This locks in juices and flavor without steaming the meat.
Finally, I return the broccoli to the pan, pour in the sauce, and stir everything until the sauce thickens and evenly coats the beef and broccoli.