Cook the pasta according to package directions.

Drain the pasta, reserving a small amount of pasta water.

While the pasta is cooking, melt butter in a large frying pan over medium heat.

Add finely chopped shallots (or crushed garlic) to the pan and sauté for about 5 minutes, until softened.

Cut the smoked salmon into thin bite-sized pieces.

Slice the green onions, separating the white and green parts.

In a small bowl, whisk together the sour cream, Dijon mustard, and white pepper.

Remove the frying pan from the heat.

Immediately stir the drained pasta into the sautéed shallots and sour cream mixture.

Add the smoked salmon and green onions to the pasta and toss gently to combine.

If the pasta seems dry, add a little of the reserved pasta water to reach your desired consistency.

Serve hot or cold.