In a medium bowl, lightly toss the crabmeat, celery, chives, and tarragon together.
In a small bowl, stir together the mayonnaise, sour cream, lemon juice, and mustard. Add the dressing to the crabmeat mixture and stir until just coated. Season with salt and pepper to taste. If not using right away refrigerate until ready to serve.
Serve on toasted rolls or on a bed of lettuce.
Yield: 4 to 6 servings