Let rice noodles soak in boiling water for 10 minutes, stirring often, until soft. For the last 3 minutes of soaking, add in the bean sprouts. Drain and set aside.
In a bowl whisk together water, hoisin, lime juice, peanut butter and Sriracha. Set aside.
Fry prawns, garlic, and ginger in oil until prawns turn pink. Stir in sauce mixture, and noodles.
Continue cooking until sauce is reduced and thickened. Season to taste with salt.
Divide among 4 bowls, and top with cilantro and peanuts.