Freeze the beef for 20 minutes to firm it up. Slice thinly against the grain—this is the difference between tender and chew toy.
In a bowl, whisk soy sauce, oyster sauce, rice vinegar, honey, sesame oil, beef broth, cornstarch, black pepper, and red pepper flakes. Reserve 2 tablespoons to toss with the sliced beef as a quick marinade.
Toss beef with 2 tablespoons of the sauce and let sit while you prep the broccoli. No long marinating needed—FYI, cornstarch acts like a velvet jacket for the beef.
Heat a large skillet or wok over medium-high. Add 1/2 teaspoon oil, then broccoli and a splash of water. Stir-fry 2–3 minutes until bright green and crisp-tender. Remove to a bowl.
Increase heat to high. Add 1/2 tablespoon oil. Spread half the beef in a single layer; don't crowd it. Sear 60–90 seconds per side. Repeat with remaining beef, adding a little more oil if needed.
Return all beef to the pan with the white parts of the green onions, garlic, and ginger. Stir 30 seconds until fragrant. Whisk the remaining sauce (cornstarch settles), then pour it in. Cook 1–2 minutes until glossy and thickened.
Add broccoli back to the pan and toss to coat. If too thick, splash in 1–2 tablespoons water. If too thin, simmer another 30–60 seconds.
Spoon over warm brown rice. Top with green onion greens, sesame seeds, and a squeeze of lime. Snap a photo, flex like you meant to do that.