In a medium size bowl whisk together the ingredients for the marinade. Add the steak and stir to coat. The mixture should be slightly thick and coat the steak strips. Cover and let sit for 15 minutes.
Bring a large pot of water to a boil, add broccoli and cook for 2-3 minutes. Strain water and set aside.
Meanwhile whisk together the ingredients for the sauce, set aside.
Heat a wok over medium-high heat and add 1 tbsp of oil. In small batches, cook the steak strips in the hot oil, about 30 seconds per side (they should be thin and cook through quickly). Remove cooked steak from wok to a warm plate. Use remaining oil if necessary to cook the remaining beef. On the last batch of beef, after you've flipped the steak strips over, add the garlic and ginger and stir until fragrant, about 30 seconds.
Return all the steak to the wok, turn heat down to medium. Pour in the sauce mixture and stir until it starts to bubble slightly. If you would like the sauce thicker, simply dissolve 1 tsp of corn starch into 1 tsp of water and pour the dissolved cornstarch into the steak strips. Let simmer until sauce thickens, about 2 to 3 minutes. Toss in the broccoli, stir to coat.
Serve over hot rice and garnish with sesame seeds and sliced green onions if desired. Enjoy!
Notes
To easily slice thin steak strips try freezing your steak for about 20 minutes before slicing.