Slice the beef thin. Freeze the steak for 20 minutes to firm it up. Slice against the grain into thin strips, about 1/4 inch. Pat dry with paper towels.

Make the sauce. In a bowl, whisk soy sauce, broth, rice vinegar, oyster/hoisin (if using), brown sugar, garlic, ginger, sesame oil, and cornstarch. Taste and adjust salt and sweetness.

Blanch or steam the broccoli. Quickly steam or blanch florets until bright green and crisp-tender (about 2 to 3 minutes). Drain well. This keeps them vibrant for meal prep.

Preheat your pan. Heat a large nonstick skillet or wok over medium-high. Add half the oil and swirl to coat.

Sear the beef fast. Add half the beef in a single layer. Don’t crowd the pan. Sear 45–60 seconds per side until browned. Remove to a plate. Repeat with remaining oil and beef.

Optional aromatics step. If using onion, toss it into the hot pan and cook 1–2 minutes to soften slightly.

Add the sauce. Reduce heat to medium. Pour in the sauce and stir. It should thicken in 30–60 seconds. If too thick, splash in a little water or broth. If too thin, simmer another minute.

Combine everything. Return beef and broccoli to the pan. Toss to coat evenly. Add chili flakes if you like heat. Cook 1 more minute to warm through.

Taste and finish. Adjust seasoning—more soy for salt, vinegar for brightness, or a pinch of sugar for balance. Garnish with green onions and sesame seeds.

Serve or portion. Spoon over rice or cauliflower rice. For meal prep, divide into 4 containers with your base of choice.