Delicate sticks of tender, mild black salsify coated in a creamy mustard dressing are a pleasing first course or salad. The texture and flavor combination is fairly rich, so plan moderate portions.
Combine lemon juice, water, and salt in a saucepan large enough to hold sliced scorzonera. Peel a scorzonera root. Cut it in 3-inch lengths, then cut each into 2 or 4 slices lengthwise, depending on thickness. Drop into the saucepan. Continue until all scorzonera is sliced. Add water, if necessary, to cover.
Bring to a boil. Cover, lower heat, and barely simmer