Smoked Chicken and Jicama Salad with Tarragon Dressing

3 tablespoons red wine vinegar
1 tablespoon Dijon mustard
1 medium shallot, very finely chopped
1/2 cup vegetable oil
1/2 cup sour cream
3 tablespoons chopped fresh tarragon
Salt and freshly ground pepper
2 whole smoked chicken breasts (about 2 pounds), skin discarded and meat cut into thin strips (see Note)
3 Belgian endives—cored, halved crosswise and thinly sliced lengthwise
1 cucumber—peeled, halved, seeded and thinly sliced
1/2 large red onion, halved lengthwise and thinly sliced crosswise
1 medium jicama (3/4 pound), peeled and cut into matchsticks
1/2 cup oil-packed sun-dried tomatoes, thinly sliced
2 bunches arugula (1/2 pound), stemmed
1/4 cup snipped chives

In a blender or food processor, blend the vinegar with the mustard and shallot until combined. With the machine on, slowly add the oil until the dressing is emulsified. Blend in the sour cream. Transfer the dressing to a small bowl and stir in the tarragon. Season the dressing with salt and pepper.
In a large bowl, toss the smoked chicken with the endives, cucumber, onion, jicama and sun-dried tomatoes. Add the tarragon dressing, season with salt and pepper and toss well. Arrange the arugula on plates and top with the chicken salad. Garnish the salads with the snipped chives and serve.

Notes If smoked chicken is unavailable, 1 1/2 pounds of smoked turkey can be substituted.