Melt butter in a large skillet over medium heat.
Add the salmon, leek, onion, and garlic, and fry until fragrant, about 2 minutes.
In a medium bowl, mix together the cream, sour cream, and cornstarch; stir into the skillet.
Stir in the lemon zest, pepper, and paprika.
Cook, stirring constantly, for 10 minutes, until sauce is thickened.
Meanwhile, bring a large pot of lightly salted water to a boil.
Add fettuccine and cook for 8 to 10 minutes or until al dente.
Drain, and toss with the salmon sauce.
Top with Parmesan cheese to serve.
Prep Time 15 Min Cook Time 20 Min Ready In 35 Min.