In a shallow dish or resealable bag, combine marinade ingredients and add the prawns. Marinade at room temperature for 30 minutes, stirring once (or flip bag).

Remove prawns from marinade (do not discard!) and set aside. Add the cornstarch-water mixture to the reserved marinade.

Heat the oil in a large saute pan over medium-high heat until oil starts to smoke. Add the aromatics (ginger, garlic, and chilli) and stir around the pan for 30 seconds.

Toss in the prawns and stir occasionally for 3 minutes.

Add scallions and stir for another 2 minutes or until prawns are completely cooked. Lower the heat to medium-low.

Give the reserved marinade a good stir until the cornstarch has been incorporated. Add this mixture to the saute pan and mix well with the prawns for 30 seconds until sauce is slightly thickened.

Serve over a bed of plain white rice and a side of vegetables.