Bring water to a boil and add seasoning (A). Put the sea cucumber in the prepared water. Allow to simmer over low heat for about 25-30 minutes. Dish out and leave to cool. Make sure the cavity of the sea cucumber is completely dry. Keep the stock aside for use later.
Mix ingredients (B) in a mixing bowl. Stir well in one direction and mix until the mixture is sticky in texture.
Place sea cucumber on a piece of cling film. Lightly dust some cornflour into the cavity of the sea cucumber. Stuff filling ingredients into the cavity and wrap up the sea cucumber with the cling film.
Tie up both ends. Place on a heatproof dish and steam for 25-30 minutes or until cooked. Remove cling film and arrange steamed sea cucumber on a serving dish.
Reheat the sea cucumber stock and bring to a quick boil. Reduce the heat and add thickening. Spoon some gravy over the sea cucumber. Cut sea cucumber into serving slices and serve garnished with kai lan stalks.
To prepare kai lan: Scald the stalks in boiling water with a pinch of sugar.