Making the Minutes Count: Prepare the sauce while the beef cooks.  Mince the garlic and grate the ginger while the vegetables cook.

1. Stir-fry beef and prepare sauce: Toss steak with soy sauce.  Heat 2 tsp oil in 12" nonstick skillet over high heat until just smoking.  Add beef and cook, stirring occasionally and breaking up clumps, until lightly browned, about 3 minutes.  (While beef cooks, prepare sauce.)  Transfer beef to clean bowl.

2. Stir-fry vegetables: Add 1 Tbsp oil to pan and return to high heat until shimmering.  Add broccoli and water to pan, cover, and cook until bright green and slightly tender, about 2 minutes.  Remove lid, add bell pepper and water chestnuts, and continue to cook until vegetables are tender, about 3 minutes.

3. Combine and simmer: Clear center of pan and add remaining 1 tsp oil, garlic, and ginger.  Cook, mashing garlic mixture into pan with back of spatula, until fragrant, about 30 seconds.  Stir in cooked beef.  Whisk sauce to recombine, add to pan, and bring to simmer.  Cook sauce until thickened, 1 to 2 minutes.  Serve immediately over rice or noodles.