Adapted from Vegetarian Cooking for Everyone by Deborah Madison

Make the mustard vinaigrette:

2 tablespoons red wine vinegar, sherry vinegar or fresh lemon juice
2 shallots, finely diced
1 garlic clove, minced
Salt and freshly ground pepper
1 tablespoon Dijon mustard
2 tablespoons creme fraiche or sour cream
1/3 cup extra virgin olive oil
2 tablespoons snipped chives
1 tablespoon chopped parsley
3 tablespoons capers, rinsed (optional), Kohlrabi and Celery with Mustard Vinaigrette

Combine the vinegar, shallots, garlic and 1/8  teaspoon salt in a small bowl. Let stand for 15 minutes, then vigorously whisk in the mustard, créme fraiche and oil until thick and smooth.  Grind in a little pepper, then stir in the herbs and capers. Taste and adjust seasoning if needed.

Make the salad:
About 12 ounces kohlrabi
4 ribs celery

Thickly peel the kohlrabi and cut into fine julienne strips.  Thinly slice the celery.  Toss together with enough mustard vinaigrette to moisten and serve.