While water is coming to a boil, whisk together all ingredients for sauce in a large pourable container. Set aside.
Add noodles to boiling water and turn heat to simmer until noodles are just cooked through. Drain and rinse with cold water. Set aside.
In a large skillet over high heat, add 1-2 Tbsp of oil. Add broccoli florets and 2 Tbsp of water. Cover, turn heat to medium and allow to steam until just barely cooked through, but broccoli still has a bite. About 3-4 minutes.
Remove cooked broccoli from pan. Turn heat back up to high and add another Tbsp of oil. Add sliced beef and allow to brown, stirring occasionally and season as needed.
Once the beef has been just cooked through, turn heat to medium, whisk sauce then add mixture to pan. Once sauce has thickened slightly, add broccoli and noodles, stir until evenly coated.
Portion into bowls and garnish with slivered onions and toasted sesame seeds.