In a bowl, combine the sauce ingredients, whisk and then set aside.
Heat oil in a wok
When hot, add the sliced beef in a single layer and saute for 2 or 3 minutes per side. (Using a Wok spatula makes this task easy)
Remove beef from the pan and add in sauce ingredients and whisk.
Bring the sauce to a simmer and reduce the heat.
Add the beef back into the pan and stir well, coating the meat with the sauce.
Add the broccoli florets and sesame seeds and lightly stir.
Cook for a few more minutes until broccoli is cooked but not soft. (4-5 minutes)
Serve hot over cauliflower rice.