In a small bowl, whisk together the soy sauce, rice vinegar, sesame oil, garlic, ginger, chili flakes, salt, pepper, and coconut sugar (add a splash of beef bone broth if using).
Brown the ground beef in a large skillet over medium-high heat, breaking it up, until no longer pink. Drain excess fat.
Add the broccoli florets and a splash of water, cover, and steam 3 to 4 minutes until tender-crisp.
Pour in the sauce and toss to coat. Simmer 2 to 3 minutes until glossy.
Serve hot over rice.