Heat 1 tablespoon of vegetable oil in a large skillet or wok over medium-high heat. Pat the chicken breasts dry with a paper towel, then season them lightly with salt and pepper. Add the chicken to the hot skillet, cooking for 5-6 minutes while turning occasionally until the chicken is browned and no longer pink in the center. Remove the chicken and set aside.

In the same skillet, add another tablespoon of vegetable oil. Toss in the minced garlic and fresh ginger, cooking for 30 seconds until fragrant.

Add the sliced mushrooms and zucchini, stir-frying for 4-5 minutes until the vegetables soften.

Return the cooked chicken to the skillet, pour in the soy sauce and sesame oil, stir to coat, and cook for another 1-2 minutes.

Add the cornstarch slurry, stirring quickly to prevent lumps. Cook for another 1-2 minutes until the sauce thickens.

Remove from heat and fold in the sliced green onions. Serve hot over rice or noodles.