In a medium bowl whisk the water, soy sauce, rice seasoning, cornstarch, ginger, sesame oil, garlic, and red pepper flakes. Set aside.
Brown ground beef in a large skillet over medium-high heat until no longer pink. Drain any grease. Add broccoli and reserved soy sauce mixture. Stir and cook until thickened and broccoli is tender-crisp. (About 3-5 minutes)