To marinate the beef, slice it thinly (this is easy if it is still a bit frozen) and combine the beef with 4 tbsp of soy sauce or coconut aminos, 2 tbsp of rice wine vinegar, and 1 tsp of sesame oil. Set aside.
Cut the broccoli into bite size pieces. Bring a pot of water to a boil and salt it liberally. Add the broccoli at once and let the pot come back to a boil. Once the pot boils, drain the broccoli and shock it in a bowl of ice water or run very cold tap water over the broccoli. Set the broccoli aside.
Finely chop the garlic and ginger. Set this aside to make the sauce.
Add 1 tbsp of oil to a large skillet and heat it over high. Working in batches, cook the beef until browned but not quite cooked all the way through, about 1-2 minutes per side. Remove the cooked beef and keep cooking the beef in batches, adding more oil as needed, until it is all browned.
Add 1 tsp of oil to the skillet. Cook the garlic and ginger over medium-high heat until fragrant and soft, about 3-4 minutes. When the garlic and ginger are cooked, add the beef broth and simmer for a few minutes to let the flavors combine. Add 2 tbps soy sauce and 1 tbsp of rice wine vinegar. Season with salt and pepper.
Optional step - thicken the sauce with 1/8 tsp of xantahn gum whisked in, or use a cornstarch slurry of 1 tbsp cornstarch mixed with 3 tbsp of cold water. If using cornstarch, you need to bring the sauce back to a boil.
Add the beef and the broccoli to the sauce and heat over high heat until warmed through and combined. Dig in!