Using your fingers tear the silverbeet from the stalks and into small pieces. In a small cup mix the mustard powder into a paste with a little of the stock and the rice syrup. Once combined add the remaining stock and mix thoroughly. Peel the garlic and cut it into fine slivers.
Heat the oil in a wok and add the garlic and prawns. Cook for 2 - 3 minutes until the prawns turn opaque. Remove from the wok and set aside. Add the silverbeet cook for 3 minutes mixing the stock mixture through as it cooks. Remove from the heat and serve with the garlic prawns on top.
Note: for extra pungency and flavour the olive oil can be substituted with pungent mustard oil when cooking the prawns.