Heat a large skillet over medium-high heat. Add the ground beef and diced onion, breaking up the beef as it cooks. Cook for 6–7 minutes, until the beef is browned and cooked through.
While the beef is cooking, whisk together soy sauce (or tamari), sesame oil, rice vinegar, fish sauce, honey, arrowroot powder, and water in a small bowl. Set aside.
Once the beef is cooked, stir in the minced garlic and grated ginger, cooking for 1 minute until fragrant.
Add the broccoli to the skillet and cover. Let the broccoli steam for 3–4 minutes, until it's bright green and tender yet crisp.
Pour the sauce over the beef and broccoli mixture, stirring until evenly coated. Let cook uncovered for 2–3 minutes to thicken the sauce.
Top with sesame seeds, chopped green onions, or a drizzle of Sriracha, if desired. Serve over rice, cauliflower rice, or enjoy it as-is!