Combine beef broth soy sauce, hoisin sauce, sesame oil, and cornstarch in a small bowl. Set aside.
In a large skillet, cook the beef and onion over medium-high until no pink remains. Drain fat.
Add the garlic and ginger and cook 2 more minutes or until fragrant. Transfer to a bowl to keep warm.
Heat oil in the pan. Add the celery and cabbage and cook for 3-4 minutes or until it begins to soften.
Add peppers and cook 2-3 minutes more.
Add the ground beef mixture, water chestnuts if using, and the sauce to the pan. Stir to combine.
Allow sauce to simmer and thicken, stirring occasionally.
Serve over rice and garnish with sesame seeds and green onions if desired.
