In a blender, combine all of the lemongrass marinade ingredients until smooth. Coat the salmon with the marinade and marinate for 4-12 hours.
Preheat the oven to 400°F.
In a blender, purée all of the coconut lime sauce ingredients until smooth. Season to taste.
Remove the salmon from the marinade, discarding excess marinade, and place on a baking sheet. Roast for 8-12 minutes, until cooked through.
Bring a large pot of water to a boil, remove the pot from the heat, and add the noodles. Let the noodles soak until tender, about 5-10 minutes. Drain.
Toss the cooked rice noodles with the bean sprouts, carrots and bell pepper and divide between plates. Top with salmon fillets, coconut lime sauce, Thai basil leaves and peanuts.