- 2 large celery roots (celeriac), about 1 pound
- 2 teaspoons fresh lemon juice
- Salt, to taste
- 1 large tart green apple (such as pippin or Granny Smith), peeled and cored
- 2 tablespoon red-wine vinegar
- ¼ cup Dijon mustard
- Salt and freshly ground black pepper, to taste
- 2 tablespoons olive oil
- 1/3 cup mayonnaise, preferably homemade or high-quality store-bought
- 2 tablespoons minced fresh parsley
- Celery root has a very tough peel and discolors easily, so work quickly. Use a sharp sturdy paring knife to cut away the peel. Rub the white flesh with a little of the lemon juice.
- Cut the celery root into chunks that will fit into the tube of a food processor fitted with the shredding blade. (You can also shred the celery root with a mandoline.) Shred the celery root, then toss in a large bowl with the remaining lemon juice and salt and cover tightly.
- Cut the apple into julienne with a sharp knife or mandoline. Toss with the shredded celery root and cover.
- Prepare the dressing: In a warm medium bowl, whisk the vinegar, mustard, salt, and pepper. Gradually whisk in the oil until emulsified. Whisk in the mayonnaise. Season with additional salt and pepper, if desired.
- Fold the dressing into the celery-root mixture and taste for seasoning, Cover and refrigerate until well-chilled. (The salad will keep for several days if kept covered and refrigerated.) When ready to serve, sprinkle with the parsley.