Soak the rice noodles in warm water for about 20 minutes until they are soft.

In a large skillet or wok, heat the vegetable oil over medium heat.

Add the sliced onion and minced garlic to the skillet. Cook until fragrant, about 2 minutes.

Stir in the carrot, bell pepper, and cabbage. Cook for another 5 minutes.

Mix in the cooked chicken or tofu, stirring well to combine.

Once the noodles are soft, drain them and add them to the skillet.

Pour in the soy sauce, oyster sauce, and sesame oil. Toss everything together.

Taste and adjust seasoning with salt and pepper as needed.