Heat oven to 450 degrees. Fold parchment pieces in half, open the fold and place one piece of salmon on bottom half, about 1 inch from the crease.
Top each fish portion with 1 tablespoon of butter, 1/2 tablespoon of herbs, then drizzle with lemon juice. Add asparagus tips and potatoes, if using. Enclose fish in parchment with a series of overlapping folds.
Place packets in a single layer on baking sheet. Bake for 6 to 10 minutes, depending on the thickness of the fish. When done the parchment paper will be puffed up and brown.