- In a bowl, combine chicken with a pinch of salt, pepper, and 1 tablespoon of soy sauce. Let it marinate for about 10 minutes. 
- Heat a large skillet or wok over medium-high heat. Add 1 tablespoon of oil. 
- Add the chicken and cook until browned and cooked through, about 5–6 minutes. Remove from pan and set aside. 
- Add the remaining oil to the pan. Toss in the garlic, ginger, and onions. Sauté for 1–2 minutes until fragrant. 
- Add broccoli, carrots, and bell pepper. Stir-fry for 3–4 minutes until vegetables are crisp-tender. 
- Return the chicken to the pan. Add oyster sauce, remaining soy sauce, and sesame oil. Stir everything together. 
- If you like a thicker sauce, stir in the cornstarch slurry and cook another 1–2 minutes until it thickens. 
- Taste and adjust seasoning with salt and pepper as needed. Serve warm with rice or on its own.