Prep all the vegetables and chicken by slicing the yellow onion, bell peppers, and carrot, chopping the cabbage, mincing the garlic, and dicing the chicken.

Heat a large skillet or wok over medium-high heat and melt 1 tablespoon of butter. Add the diced chicken and cook for about 5–7 minutes until golden brown and fully cooked.

In the same skillet, add another teaspoon of butter if needed, then toss in the sliced onion and minced garlic. Stir-fry for 1–2 minutes until the onion is translucent and fragrant.

Add chopped cabbage, bell peppers, and carrot to the skillet. Stir continuously for about 5 minutes until the vegetables are crisp-tender.

Return the cooked chicken to the pan along with the sautéed vegetables. Pour in the soy sauce, oyster sauce, and sesame oil, stirring thoroughly.

For a thicker sauce, mix 1 tablespoon of cornstarch with 2 tablespoons of water, add to the skillet, and stir continuously until thickened, about 1 minute.

Serve immediately over steamed rice or noodles, garnished with sesame seeds or chopped green onions.