Beef and Broccoli Ramen Noodle Stir-Fry

0 Transfer steak to the freezer for 10 minutes (cold steak is easier to slice).
1 If using frozen broccoli, defrost it in the microwave. If using fresh broccoli, put it in a microwave-safe bowl with 2 Tbsp of water. Cover with paper towels and microwave on high until nearly tender, ~3 minutes.
2 Heat a pot or bowl of water in the microwave or on the stove until steaming. Add noodles and let them soak until just tender. (Check the package instructions for the recommended timing, but reduce it by about a minute since the noodles will continue to cook in the stir-fry.) Drain. 
3 In a small bowl, make sauce by whisking together soy sauce and cornstarch until no lumps remain. Add water, brown sugar, rice vinegar, toasted sesame oil, and garlic. Set aside. 
4 Remove the steak from the freezer and cut it into thin slices against the grain (position your knife in the opposite direction of the natural lines that run through the meat). Season the steak with some salt and pepper.
5 Heat a wok or large skillet over medium-high heat. Add 1 Tablespoon of oil and then steak. Sauté until steak is just cooked through and golden brown, 4 to 5 minutes.
6 Add broccoli and sauce to steak and cook until sauce thickens, ~2 minutes.
7 Add noodles and toss everything to coat.
8 Serve stir-fry with green onions and sesame seeds on top.