Combine all the ingredients for the velveting mixture in a bowl and mix well.
Add sliced beef to mixture, mixing well and allow to marinate for 20 minutes.
Mix sauce ingredients together in another bowl.
Heat vegetable oil in a wok or large saute pan over high heat until it begins to shimmer. It should be about 350 degrees.
Add the beef to the pan and quickly fry it for 1-2 minutes until beef is almost done and the exterior has turned nicely brown.
Remove the beef from the pan and place over a wire grate to allow it to drain.
Pour the oil out of the pan, reserving 2 tablespoons. Rinse the pan with water, getting rid of any excess residue by scraping the pan. Dry pan and return to heat.
Add the 2 tablespoons of oil back to the pan. Add in ginger, garlic and scallions(white). Saute for about 45 seconds until fragrant.
Return beef to pan along with broccoli florets and peppercorns. Saute for about 1 minute then add in the sauce mixture.
Cook for about 2 minutes until the sauce mixture thickens. Serve and garnish with scallions (green)