Thinly slice the chicken breasts. Slice the red bell pepper and zucchini, cut the broccoli into florets, and mince the garlic.
Heat the olive oil in a large skillet or frying pan over medium-high heat. Add the sliced chicken and season lightly with salt and black pepper. Cook for 4–5 minutes, stirring occasionally, until the chicken is fully cooked and lightly golden.
Add the minced garlic to the pan. Stir and cook for about 30 seconds until fragrant.
Add the broccoli, red bell pepper, and zucchini to the pan. Stir well and cook for 3–4 minutes until the vegetables are tender-crisp.
Pour in the soy sauce, oyster sauce, and sesame oil. Stir everything together so the chicken and vegetables are evenly coated.
Cook for another 1–2 minutes, stirring frequently, until the sauce is heated through and the vegetables are cooked to your liking.
Taste and add more salt if needed. Serve immediately while hot and enjoy your healthy low carb chicken stir fry.