Thinly slice the chicken breasts into strips, slice the onion and orange pepper, mince the garlic, finely dice the jalapeño pepper, and shred the green cabbage.
Melt the butter over medium-high heat, add sliced chicken, season with salt and pepper, and stir-fry until cooked through and lightly browned (5-7 minutes). Remove chicken and set aside.
In the same skillet, add sliced onion and sauté until softened (about 3 minutes). Add minced garlic and diced jalapeño; sauté for an additional minute. Then add shredded cabbage and diced orange pepper.
Pour in chicken stock, oyster sauce, and soy sauce. Stir well and cook until cabbage is tender-crisp (5-7 minutes).
Return the cooked chicken to the skillet, mix everything thoroughly, and cook for another 2-3 minutes until heated through. Adjust seasoning if necessary before serving hot.