In a large bowl, mix together the flour, salt, and oil. Gradually add the warm water and knead to make a soft dough. Cover with a damp cloth and set aside for 30 minutes.
Heat the ghee in a large skillet over medium heat. Add the cumin seeds and cook for 1 minute. Add the potatoes, turmeric powder, and salt to taste. Cook until the potatoes are tender.
Divide the dough into 12 equal portions. Roll each portion into a 4-inch circle. Place 2 tablespoons of the potato mixture in the center of each circle.
Fold one side of each circle over to form a semi-circle shape. Pinch along the edges to seal in the filling. Heat oil in a deep skillet over medium heat. Fry samosas until golden brown.