Bring 8 cups of water to a boil. Place the noodles in a heatproof bowl. Pour the boiling water over them and soak 1 to 2 minutes, until softened. Drain the noodles well, cool in ice-cold water, drain well again and place back in the bowl. Toss with the sesame oil and set aside.
Place 2 Tbsp. of the vegetable oil in a large skillet or wok set over medium-high heat. Add the prawns and cook and stir 2 to 3 minutes, or until just cooked through. Add the lime juice and soy sauce. Transfer prawns and liquid in the wok or skillet to a shallow bowl.
Wipe the skillet or wok clean. Place the remaining 3 Tbsp. vegetable oil in the pan and set back over medium-high heat. Add the ginger and bell pepper and cook 1 minute. Add curry powder and cook 30 seconds more. Add the noodles, prawns, green onion, beans sprouts and stock and toss and cook 2 minutes, or until all are heated through. Spoon noodles onto a platter, sprinkle with cilantro and enjoy.