Chinese Broccoli in Ginger Sauce

Name: Chinese Broccoli in Ginger Sauce (Jiang Zhi Jie Lan 薑汁芥藍)
Cuisine: British
Ingredients: ½ tsp caster sugar; 1 tsp potato flour mixed with 1 tbsp cold water (optional); 2 tbsp finely chopped ginger; 1 tbsp Shaoxing wine; Salt; 4 tbsp cooking oil; 350 g Chinese broccoli