Heat oven to 450°F. Spray 15x10x1-inch rimmed sheet pan with cooking spray.
In large bowl, mix dressing and 2 teaspoon of the soy sauce; add broccoli, and toss to coat. Pour broccoli mixture onto pan, spread in single layer.
In same bowl, mix brown sugar, garlic, salt and remaining 4 teaspoons soy sauce. Add beef to mixture; turn to coat.
Add beef to pan with broccoli. Roast 10 to 14 minutes or until beef is cooked to desired doneness (145°F for medium-rare) and broccoli is fork-tender.
Sprinkle with sesame seed. (optional)