Preheat the oven to 375 degrees. Prick the potatoes with a fork. Bake for 1 hour, or until soft. Cut the potatoes in half, scoop out the flesh and set aside. Heat the oil in a nonstick frying pan and fry the onion for a few minutes to soften. Stir in the ginger, cumin, coriander and turmeric. Stir over low heat for about 2 minutes, then add the potato flesh and garlic salt to taste. Cook the potato mixture for another 2 minutes, stirring occasionally. Spoon the mixture back into the potato shells and top each with a spoonful of plain yogurt and a sprig or two of cilantro. Serve hot.
Serves 2-4