Penne with Smoked Trout, Cream and Asparagus

cut into 2-inch pieces, tough ends discarded

large, finely chopped

or other sturdy smoked fish, broken into bite-size pieces

tightly packed, like dill, basil, tarragon, chives, mint and thyme, any combination will work, roughly chopped, plus 1/4 cup more for garnish

Grated zest of, large, plus lemon juice as needed