Cut a thin slice off the top and bottom of each potato. Cut the potatoes in half crosswise. Place in a large saucepan and cover with the water. Add the kosher salt. Bring to a boil over high heat. Reduce the heat and let simmer. Cook until the potatoes are tender when pierced with a fork. 10 to 15 minutes. Be careful not to overcook. Strain and let cool.
Crumble the feta with a fork in a small bowl. Add the pine nuts, green olives, olive oil, currants, lemon zest, oregano and pepper. Mix well.
Scoop out the center of each potato with a spoon or melon baller. Fill the centers with a heaping teaspoon of the feta mixture. Garnish with a parsley leaf.