Prep the chicken: Pat chicken dry with paper towels. Slice thinly against the grain. Toss with 1 tbsp cornstarch and a pinch of salt.
This light coating helps sear and keeps the chicken tender.
Make the sauce: In a small bowl, whisk soy sauce, water, honey, rice vinegar, sesame oil, cornstarch, garlic, ginger, and red pepper flakes if using. Set aside.
Heat the pan: Place a large skillet or wok over medium-high heat. Add 1 tbsp oil and swirl to coat until shimmering.
Sear the chicken: Add chicken in a single layer (cook in two batches if needed).
Don’t crowd the pan. Cook 2–3 minutes per side until lightly browned and just cooked through. Transfer to a plate.
Stir-fry the veggies: If the pan looks dry, add 1 tsp more oil.
Add broccoli and carrot first; stir-fry 2 minutes. Add bell pepper and red onion; cook another 2–3 minutes until crisp-tender.
Add aromatics: Push veggies to the sides. Add garlic and ginger to the center; stir 20–30 seconds until fragrant.
Combine and sauce: Return chicken and any juices to the pan.
Whisk the sauce again (cornstarch settles) and pour it in. Stir constantly 1–2 minutes until the sauce thickens and glazes everything.
Finish and garnish: Turn off heat. Taste and adjust—more soy for salt, a splash of water to loosen, or a drizzle of honey for sweetness.
Top with green onions and sesame seeds.
Serve: Spoon over your choice of rice or grains. A squeeze of lime adds a bright finish.