|fresh lemon juice, or to taste
|drained bottled horseradish, or to taste
|finely chopped scallion green finely chopped scallion green finely chopped scallion green
In a steamer set over boiling water steam the fiddleheads for 5 minutes, or until they are crisp-tender, transfer them with a slotted spoon to a bowl of ice and cold water to stop the cooking, and transfer them to paper towels to drain.
In a small bowl whisk together the yogurt, the mayonnaise, the lemon juice, the mustard, the horseradish, the scallion, and salt and pepper to taste, whisking until the sauce is smooth, and serve the fiddleheads topped with the sauce.