Grate 20 grams of truffle in a bowl chop finely the spring onion and add to the grated truffle. Cook the pasta info plenty of salty water, drain it and pour it on the truffle with spring onions. Add the salmon cut into pieces, the olive oil and mix up. If you prefer using a fresh salmon you can steam it and season it with salt and oil. Leave it in the fridge to cool down. When you serve add the best of the truffle cut into fine slices.