Wash, peel and cook the potatoes (about 30 minutes). Chop the dill.
In a small bowl mix lemon juice, yogurt, a pinch of salt, olive oil and vinegar. Add chopped dill and the capers. Season with pepper to taste.
When the potatoes are done, drain them and cut them into thin slices. Put into a salad dish. Pour the dressing on top and mix to coat all the potatoes with it. Using your fingers crumble the feta cheese over the salad.
Cut the green onions/scallions into thin slices, chop the olives and add as well.