Heat 1 tablespoon of oil in a wok or large skillet over medium-high heat. Add chicken slices and stir-fry for 4–5 minutes until cooked through. Remove and set aside.
In the same pan, add remaining oil. Stir-fry garlic, bell pepper, broccoli, snow peas, and carrot for about 4–5 minutes until tender-crisp.
Return chicken to the pan. Add soy sauce, oyster sauce, and cornstarch slurry. Toss everything until the sauce thickens slightly and coats the chicken and vegetables.
Adjust seasoning with salt and pepper. Serve hot over steamed rice.