In a medium bowl, whisk together the light soy sauce, rice vinegar, sesame oil, and cornstarch until smooth. Add the boneless and skinless chicken breast, ensuring it is well-coated in the marinade. Cover and let marinate for 20-30 minutes in the refrigerator.

While the chicken marinates, mix together the water, additional soy sauce, rice vinegar, brown sugar, and cornstarch in a separate bowl until smooth. Set aside for later use.

In a large skillet or wok, heat about 2 tablespoons of vegetable oil over high heat. Wait until the oil shimmers slightly before adding any ingredients.

Carefully add the marinated chicken to the skillet in a single layer. Cook for about 4-5 minutes without stirring to develop a crust, then flip to brown the other side and cook through. Remove from skillet and set aside.

In the same skillet, add the cleaned and quartered mushrooms and sliced zucchini. Sauté for about 2-3 minutes until crisp-tender.

Lower the heat to medium-low and return the cooked chicken to the skillet. Add the minced garlic and ginger, cooking for about 1 minute until fragrant.

Pour the sauce mixture into the skillet, tossing everything together until evenly coated. Continue cooking for 1-2 minutes as the sauce thickens.

Serve immediately over jasmine rice or noodles. Enjoy!