This recipe, originally created by Chef Ilene Rosen, has been modified by WW with permission.
Put scallions in bowl of a food processor or in a blender; add yogurt, lemon juice and lemon zest; pulse to combine. With the motor still running, drizzle in oil; process until smooth. Season to taste with salt and pepper; set aside.
Put potatoes in a large saucepan and add salted water to cover by 2 inches; bring to a gentle boil over high heat. When potatoes are just tender enough to be pierced through easily with the tip of a sharp knife, 10-12 minutes depending on size, drain in a colander.
When potatoes are cool enough to handle, cut them in half; transfer to a serving bowl. Add ½ c dressing and toss gently, taking care not to break potatoes; season to taste with salt and pepper. Let potatoes cool completely.
When ready to serve, add 1 1/2 c herbs, celery, celery seed and remaining dressing to potatoes; toss to combine. Sprinkle salad with remaining 1/2 c herbs; serve.
Use any combination of whole mint leaves, small dill and/or tarragon sprigs, lovage or celery leaves (torn if large), and long cuts of chives.