Cut the Chinese cabbage into wide strips, rinse. Heat half of the oil and let the sugar melt in it. Once the sugar caramelizes, add the dripping cabbage, stir well. Season with soy sauce and vinegar. Cover and steam for 15 minutes.
Sauté meat strips in remaining oil, season. Drain tomatoes, add to cabbage form with meat. Mix flour with cold water, thicken the dish with it. Season with Chinese seasoning and sherry.
Serve with long grain rice.