Bring to a rolling boil in a large pot:
6 quarts water
2 tablespoons salt
Add and cook until tender but firm, 1 to 4 minutes depending on their thickness:
1 pound fresh asparagus, tough ends trimmed, cut into 1-inch pieces.
Scoop out the asparagus with a sieve and rinse under cold water to stop the cooking and preserve the bright green color. Return the cooking liquid to a rolling boil.
Add and cook until tender but firn:
1 1/4 Pounds fresh spinach fettuccine, or 1 pound dried.
Meanwhile, melt in a large skillet over medium heat:
3 tablespoons unsalted butter
Add the asparagus and cook, stirring, just to coat with butter, about 1 minute. Stir in and heat through:
1 cup heavy cream
Grated zest of 1 lemon
Drain the pasta and add it to the skillet along with:
4 ounces smoked salmon, cut into thin strips, or cooked fresh salmon, cut into small pieces
1/4 cup snipped fresh chives
1/4 cup chopped fresh parsley
Salt and ground black pepper to taste
Toss to combine and serve immediately.