In a bowl, mix soy sauce, dry sherry, and cornstarch. Add chicken pieces and marinate for 10 minutes.
Heat 1 tablespoon of vegetable oil in a skillet over medium-high heat. Add chicken and cook until golden, then set aside.
In the same skillet, add another tablespoon of oil. Stir-fry zucchini, bell pepper, and broccoli for 3-4 minutes until crisp-tender.
Add minced garlic and green onions, stir-frying for another 30 seconds until fragrant.
Return the chicken to the skillet and pour in the chicken broth. Stir well to combine all ingredients.
Cook for another 2 minutes until the sauce thickens slightly.
Remove from heat and serve hot.
Enjoy with rice, noodles, or on its own!