Prep the chicken: Slice chicken thinly against the grain so it cooks quickly and stays tender.
Pat it dry with paper towels to help it sear instead of steam.
Quick marinade: In a bowl, toss chicken with 1 tablespoon soy sauce, 1 teaspoon cornstarch, and 1 teaspoon oil. Let sit while you prep the sauce and vegetables (about 10 minutes).
Mix the sauce: In a measuring cup, whisk 1/3 cup soy sauce, 1/2 cup chicken broth, 1–2 tablespoons oyster sauce, 1–2 tablespoons honey or brown sugar, 1 tablespoon rice vinegar, 1 teaspoon sesame oil, and 2 teaspoons cornstarch. Adjust sweetness and salt to taste.
Prep the aromatics: Mince the garlic and grate the ginger.
Slice green onions if using. Keep them close to the stove; the cooking goes fast.
Blanch or steam the broccoli (optional but helpful): For super crisp-tender florets, briefly steam or blanch the broccoli for 1–2 minutes, then drain well. This step helps if your pan is small or your broccoli is very dense.
Heat the pan properly: Set a large skillet or wok over medium-high to high heat.
Add 1 tablespoon oil and swirl to coat. A hot pan is key for good color and quick cooking.
Cook the chicken in batches: Add half the chicken in a single layer. Let it sear undisturbed for 1–2 minutes, then stir-fry until just cooked through, about 3–4 minutes total.
Transfer to a plate and repeat with the remaining chicken, adding more oil if needed.
Stir-fry the aromatics: Lower heat slightly if the pan is smoking. Add a small splash of oil, then the garlic and ginger. Stir for 20–30 seconds until fragrant—don’t let them burn.
Add the broccoli: Toss in the broccoli and stir-fry for 1–2 minutes to heat through and pick up flavor.
If you skipped blanching, cook a bit longer and add a splash of water to help it soften.
Combine everything: Return the chicken and any juices to the pan. Give the sauce a quick stir (cornstarch settles), then pour it in. Stir continuously for 1–2 minutes until the sauce thickens and coats everything.
Finish and serve: Stir in green onions and a pinch of red pepper flakes if you like heat.
Taste and adjust with a dash more soy for salt, honey for sweetness, or vinegar for brightness. Serve hot over rice or noodles and sprinkle with sesame seeds.