Place vodka, cream and crème fraîche into a wide deepish saucepan and bring to the boil. Turn to a simmer and cook until reduced by one-third.
Meanwhile, bring a large saucepan of salted water to the boil and cook tagliatelle until al dente. Drain in a colander then tip into a bowl.
Add butter to the creams and turn up heat. Gently mix in the salmon, then take off the heat and a