Cover the potatoes with the stock and enough water to cover the potatoes by 1 inch. Bring to a boil and cook the potatoes for 12-15 minutes, until tender. Drain the potatoes and place them back in the hot pot.
Combine the scallions, celery, vinegar, sugar, horseradish and EVOO in a small bowl. Pour over the hot potatoes to absorb.
Season the salad with celery seed, dill, salt and pepper. Toss to serve.