How to Make It
Bring a large saucepan of salted water to a boil. Add potatoes; reduce heat to a brisk simmer and cook until potatoes are easily pierced with a knife, about 15 minutes. Transfer to a paper towel-lined plate and let cool completely. (You may cover and refrigerate potatoes at this point for up to 1 day. Bring to room temperature before continuing.)
In a small bowl, whisk together yogurt and lemon juice.
Slice potatoes in half crosswise. Thinly slice off ends to help them sit flat. Arrange on a platter. Top each potato half with 1/4 tsp. each yogurt mixture and caviar. Garnish with snipped chives and serve.