Slice the chicken thinly across the grain. Cut zucchini into half-moons about 1/4 inch thick. Mix soy sauce, rice vinegar, honey, grated ginger, and sesame oil in a small bowl.
Heat 1 tbsp oil in a large skillet or wok over medium-high heat. Add chicken in a single layer, season with salt and pepper, and sear 2–3 minutes per side until cooked through. Remove chicken to a plate.
Add remaining oil to the pan. Cook onion 2 minutes until softened, add garlic for 30 seconds. Add zucchini and stir-fry 3–4 minutes until tender-crisp.
Return chicken to the pan, pour in the sauce and chicken broth, and bring to a simmer. Stir in the cornstarch slurry and cook 1–2 minutes until sauce thickens and coats everything.
Adjust seasoning, squeeze lime if desired, and garnish with sesame seeds and green onions. Serve over rice, noodles, or in lettuce cups.
Notes
Pat chicken dry before cooking to ensure good browning.
Cook zucchini quickly over high heat to keep it from becoming watery.
Prep sauce and veggies ahead to speed up weeknight cooking.