In a saucepan, cover the potatoes with salted water. Bring to a boil and cook over medium heat until they are tender. Run under cold water. Drain and let cool completely.
Cut the potatoes up 3/4 of the height to form a cap. With a melon baller, remove a little ball of flesh from each potato. If necessary, cut a thin slice at the base to keep the potatoes stable. In a bowl, combine the yogurt, watercress and lime juice. Season with salt and pepper.
Stuff 3/4 of each potato with the yogurt mixture. Garnish with smoked salmon. Top with the cap. If desired, garnish with chives.
These potatoes can be prepared the day before. Just cover and keep refrigerated overnight.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.