2) Meanwhile, in a small saucepan, whisk together the orange juice, lime juice, ginger, cornflour and garlic powder. Set the pan over a medium heat and bring to a simmer. Simmer 2 minutes, until the mixture thickens. Season, to taste, with salt and black pepper. Transfer the sauce to a serving bowl.
3) Serve the prawns with the rice and dipping sauce on the side.