Melt butter: In a large skillet over medium heat, add 1 tbsp of butter and let it melt completely, ensuring it coats the bottom of the pan.
Sauté onions: Add the 1 medium sliced onion to the skillet. Sauté for about 3-4 minutes until the onion becomes soft and translucent.
Add garlic: Toss in 2 minced garlic cloves into the skillet. Cook for another minute, stirring frequently, until fragrant.
Cook chicken: Incorporate 2 thinly sliced chicken breasts. Cook for 5-7 minutes, stirring often, until the chicken is cooked through and no longer pink.
Add vegetables: Stir in 1/2 head of shredded cabbage, 1/2 finely diced jalapeño, and 1 diced orange pepper. Cook for about 4-5 minutes, or until the cabbage is tender yet still slightly crisp.
Incorporate liquids: Pour in 1/2 cup chicken stock, 2 tbsp oyster sauce, and 1 tbsp soy sauce. Stir well to combine and season with salt and pepper to taste.
Simmer: Let the mixture simmer for 2-3 minutes, allowing the flavors to meld and the sauce to slightly thicken.
Serve: Serve the stir-fry warm, ideally over steamed rice or noodles to soak up the delicious sauce.