Prepare all your ingredients: thinly slice the chicken, shred the cabbage, and slice the bell pepper and onion. Mince the garlic and ginger.
Heat the vegetable oil in a wok or large skillet over medium-high heat. Add the sliced chicken, season with salt and pepper, and cook for about 5-7 minutes, stirring frequently, until the chicken is cooked through and slightly golden.
Add the onion, bell pepper, garlic, and ginger to the wok. Stir-fry for 2-3 minutes until the vegetables start to soften.
Stir in the shredded cabbage and cook for another 2 minutes until the cabbage is wilted but still crunchy.
Pour in the soy sauce and oyster sauce (if using), mixing everything well to ensure the chicken and vegetables are evenly coated with the sauce. Cook for an additional 1-2 minutes.
Drizzle the sesame oil over the stir-fry and mix well. Taste and adjust seasoning with more salt, pepper, or soy sauce if needed.
Remove from heat and transfer to a serving platter. Garnish with sesame seeds and fresh cilantro if desired.
Serve hot and enjoy your Chicken Cabbage Stir Fry!