Wash the salmon fillets, pat dry and cut into bite-sized cubes. Sprinkle with salt and drizzle with lemon juice.
Cook the pasta according to the instructions on the packet.
In the meantime cut the onion into small cubes and fry until translucent. Then add the salmon cubes and fry for about 5 - 8 minutes. Add the creamed spinach and heat. Season to taste with salt, pepper and mustard.
Drain the pasta, rinse with cold water and mix into the spinach mixture.