Coat the Chicken: Toss the chicken pieces with 3 tablespoons of cornstarch, making sure it’s evenly coated.
Cook the Chicken: Heat 2 tablespoons of olive oil in a large skillet over medium-high heat. Add the chicken and cook for about 5–6 minutes, flipping once, until browned and cooked through. Remove the chicken from the skillet and set aside.
Cook the Vegetables: In the same skillet, add the sliced mushrooms and zucchini. Cook on high heat for 3–4 minutes, stirring occasionally.
Add Garlic and Ginger: Add the minced garlic and grated ginger to the skillet, stirring constantly for about 30 seconds until fragrant.
Return Chicken: Return the cooked chicken to the skillet. Add the soy sauce, lime juice, and brown sugar, stirring to coat the chicken and vegetables in the sauce.
Thicken the Sauce: In a small bowl, combine 1 teaspoon cornstarch with 2 tablespoons of water. Pour this slurry into the skillet and cook for another 1–2 minutes, until the sauce thickens to a glossy consistency.
Garnish and Serve: Sprinkle sesame seeds on top for garnish, if desired, and serve hot.