In a medium saucepan bring two cups of water to a boil. Cook asparagus in boiling water for 3 minutes. Drain, reserving 2 tablespoons of liquid.
Heat the oil in a frypan over medium-high heat. Saute the prawns pieces until the colour changes, about 3 to 5 minutes. Stir in asparagus with reserved liquid and season with ginger, soy sauce, sugar, sherry and salt to taste. Continue to cook for 5 more minutes.