Heat the oil in a wok over medium-high heat. Fry the liver strips on all sides until cooked through with no pink remaining, about 3-4 minutes. Remove to a plate, season with salt and pepper, and set aside to keep warm.
In the same wok, add the soy sauce and sherry, then add the onion rings. Sauté over medium heat for 2-3 minutes until softened.
Pour in the meat broth and bring to a gentle simmer.
Add the red pepper strips and green pepper strips. Cook for 1 minute, then add the bamboo shoots and savoy cabbage strips. Continue cooking for 2 minutes more.
Add the bean sprouts and cook for 1 minute until all vegetables are tender but still have bite. Season with salt, pepper, and a pinch of sugar to taste.
Mix the cornstarch with some water to form a smooth paste. Stir into the wok and cook for about 1 minute until the sauce thickens.
Return the liver strips to the wok and stir everything together. Heat through for 1-2 minutes.