Over medium heat, sauté onion in a large skillet with the olive oil and butter. When the onion is translucent, add the salmon and cook over a medium heat for about 2 minutes. Add the vodka and cook for a a few more minutes. Add the tomato puree, and cook for additional 10 minutes, until the liquid has partially evaporated. Add the cream and cook for about 5 additional minutes, until the cream has slightly reduced. Add salt and pepper to taste.
Meanwhile, bring a large pot of salted water to a boil. Cook the pasta until al dente. Drain, and add to the salmon mixture.