Smooth Dijon and grainy Pommery mustards unite to form a dramatic dressing for lightly cooked strips of celeriac.
4 medium celeriacs, unpeeled
3/4 cup mayonnaise, preferably homemade
3/4 cup sour cream
1/3 cup Dijon mustard
1/4 cup Pommery whole-grain mustard
1 teaspoon sugar
3 tablespoons lemon juice
1 teaspoon dried tarragon
Salt and freshly ground white pepper
1. Drop the celeriacs into a large pot of boiling salted water and cook, uncovered, at a gentle bubble for 20 minutes or until crisp-tender. Drain in a colander. When cool enough to handle, peel the celeriacs and slice thinly. Cut the slices into julienne strips and transfer to a large bowl.
2. In a small bowl, whisk together the mayonnaise, sour cream, Dijon mustard, and Pommery mustard. Blend in the sugar, lemon juice, and tarragon.
3. Sprinkle the celeriac with salt and pepper to taste. Then pour on the mustard mixture and toss to coat evenly. Cover the bowl and chill thoroughly. Spoon onto glass salad plates to serve.