1. Sift the flour and salt into a bowl. Add the 4 tablespoons on oil
and rub it in with your fingers until the mixture resembles coarse
2. Slowly add about 4 tablespoons water- or a tiny bit more -- and gather the dough into a stiff ball.
3. Empty the ball out on to clean work surface. Knead the dough for about 10 minutes or until it is smooth. Make a ball. Rub the ball with about 1/4 teaspoon oil and slip it into a plastic bag. Set aside for 30 minutes or longer.
4. Make the stuffing. Peel the potatoes and cut them into 1/4 inch dice.
5. Heat 4 tablespoons oil in a large frying pan over a medium flame. When hot, add the onion. Stir and fry until soft but not brown. Add the peas, ginger, green chilli, fresh coriander (cilantro), and 3 tablespoons water. Cover, lower heat and simmer until peas are cooked. Stir and add a little more water if the frying pan seems to dry out.
6. Add the diced potatoes, salt, coriander seeds, garam masala, roasted cumin, chilli powder and lemon juice. Stir gently to mix. Adjust the seasoning with salt and pepper. Turn off the heat and allow the mixture to cool.
7. Knead the pastry dough again and divide it into six balls. Keep 5 covered while you work with the sixth.
8. Roll this ball out into a 7 inch (18 cm) round. Cut it into half with a sharp, pointed knife. Pick up one half and form a cone, making a 1/4 inch wide (5 mm), overlapping seam. Glue this seam together with a little water. Fill the cone with about 2 1/2 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 1/4 inch (5 mm) wide. Press the top seam down with the prongs of a fork or flute it with your fingers. Make another samosa from other half. Make 12 more samosas.
Heat about 2 to 3 inches of oil in a karahi for deep frying over a medium-low flame. You may use a small, deep, frying pan for frying. When the oil is medium 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. Drain on paper towel and serve hot.
Ready made pastry wrap can be purchased from supermarket or oriental stores.