Thinly slice the chicken breasts into strips. This ensures they cook quickly and evenly in the stir-fry.
Slice the onion and orange pepper, mince the garlic, and finely dice the jalapeño pepper. Preparing these ingredients ahead of time allows for a more organized cooking process.
Shred the green cabbage. The cabbage should be in bite-sized pieces to ensure it cooks evenly and blends well with the chicken.
In a large skillet or wok, melt the butter over medium-high heat. Once the butter is sizzling, add the sliced chicken breasts. Season with a pinch of salt and pepper and stir-fry the chicken until fully cooked through and lightly browned, approximately 5-7 minutes. This step is crucial for ensuring your chicken remains juicy.
Transfer the cooked chicken from the skillet and set it aside. In the same skillet, add the sliced onion and stir-fry until it begins to soften, about 3 minutes. Next, add the minced garlic and diced jalapeño pepper, cooking for an additional minute while stirring frequently to release their flavors.
Then, add the shredded cabbage and diced orange pepper. Pour in the chicken stock and stir to combine. Add the oyster sauce and soy sauce, ensuring the vegetables are coated evenly. Cook for an additional 5-7 minutes, until the cabbage is tender yet still slightly crisp.
Finally, return the cooked chicken to the skillet, mixing it with the vegetables and sauce. Cook for another 2-3 minutes to heat the chicken through and allow the flavors to meld together. Taste and adjust seasoning with more salt and pepper if required.
Transfer the stir-fry to a serving dish. Serve hot, either on its own or over a bed of steamed rice or noodles.