Thinly slice steak into 1/2 to 1 inch pieces, cutting against the grain. Then, whisk 1 tbsp cornstarch, 3 tbsp soy sauce, 1 tsp sugar, and 1 tbsp avocado oil in a large bowl. Add the steak and toss to coat, then set aside.
Whisk the remaining 1 tbsp cornstarch and 1 tbsp soy sauce with oyster sauce and beef bone broth broth in a small bowl and set aside (this will be your simmer sauce).
Heat 1-2 tbsp avocado oil in a large non-stick skillet or wok over medium high heat. Add garlic and steak, then sprinkle 2 tsp of sugar on top. Stir fry continuously until steak is medium rare.
Add your simmer sauce in the wok and reduce heat to medium-medium low until sauce begins to thicken. Add onion, broccoli, and ginger, and cook until broccoli is bright green.
Serve over rice and sprinkle with sesame seeds, if desired.