Fiddleheads lend themselves to many of the same preparations as asparagus. Here they are served warm, but they also make good hors d'oeuvres served in a vinaigrette.
Remove the dry, sheathlike papery particles from the fiddleheads. Fill a medium bowl with cool water; add 1 teaspoon salt and the lemon juice. Add ferns, and push them down into the water several times to clean them. Transfer to paper towel to drain.
On a steamer rack set over an inch of water in a saucepan, steam fiddleheads, covered, until tender, 4 to 5 minutes.
Melt butter in a large skillet over medium heat. Add fiddleheads, and cook 1 to 2 minutes on each side, until golden. Season with salt and pepper, and serve.