1) Knead the pastry dough again with hands and divide it into eight balls. Keep all balls covered while you work on one at a time. Roll each ball out into a 7 inch (18 cm) round. Cut it in half with a knife.
2) Pick up one half and form a cone out of it, making a ¼ inch wide (5 mm), overlapping seam. Glue the seam together with a little water. Fill the cone with about 2 ½ tablespoons of the potato mixture. Close the top of the cone by sticking the open edges together with a little water. Again, your seam should be about ¼ inch (5 mm) wide.
3) Press the top seam down with the prongs of a fork or flute it with your fingers. Repeat this process for each remaining balls.
4) Heat about 1 ½ to 2 inches (4-5 cm) of oil for deep frying over a medium-low flame. You may use a small, deep, frying pan. When the oil is hot, put in as many samosas as the pan will hold in a single layer. Fry slowly, turning the samosas frequently until they are golden brown and crisp.
5) Put each fried samosa on a paper towel to absorb any access oil.