Slice the flank steak into thin strips against the grain to ensure tenderness.
In a small bowl, whisk together the tamari, honey, minced ginger, minced garlic, red pepper flakes, and water to create the sauce.
Heat the toasted sesame oil in a large skillet or wok over medium-high heat.
Add the beef strips to the skillet in a single layer and sear until browned, about 2-3 minutes, then transfer the beef to a plate.
Add the broccoli florets and a splash of water to the same skillet, cover with a lid, and steam for 2 minutes until bright green and tender-crisp.
Stir in the cauliflower rice and cook for an additional 2 minutes until softened.
Return the beef to the skillet and pour the prepared sauce over the mixture, tossing constantly until the sauce thickens and coats all ingredients.
Serve the stir-fry immediately in a bowl, garnished with a sprinkle of sesame seeds.