In a pot with salted water, boil the tagliatelle with the cube of vegetable juice for 7-8 minutes. Put the olive oil in a big fry pan and brown the onion, the garlic and then the shrimps.
In a fry pan for paella or in a similar, wide cooking vessel boil the olive oil up. Then pour the garlic and the shrimps and stir them until they get a slight red color. Then add the mussels and the paprika.
Boil the noodles in well salted and well boiled water and strain them. Slightly oil them and mix them up. In a small saucepan put all the ingredients for the sauce apart from the corn flour.