In a small bowl, toss beef with 2 T cornstarch.
Heat oil in a wok or deep pan over medium-high heat. Add beef, cooking until medium-well done (~5 minutes). Transfer beef to a separate plate.
Add 1/2 c broth to wok with broccoli. Cover and cook, stirring occasionally, until broccoli is almost crisp (~4 minutes).
In a small bowl, stir together ginger, garlic, water, soy sauce, remaining 1/2 c broth, and remaining 1/2 T cornstarch until well blended.
Add soy sauce mixture to wok. Bring to a simmer, continuously stirring until slightly thickened (~2 minutes).
Return beef to wok and toss to coat.
Serve immediately.