Bring to boil a pot of water, add 1 teaspoon of salt and 1 teaspoon of palm oil before adding siew pak choy. Allow the leaves to turn dark green before draining it. Set aside to cool and arrange on plate.
Heat oil in wok. Fry shallots and prawns till prawns turn red. Remove prawns and arrange over the blanched siew pak choy.
Add hot water to remaining gravy on the wok and seasoning before thickening it with corn starch. Pour gravy over prawns and siew pak choy.