Making the pastry:
Sieve the flour into a bowl, add salt and oil and rub the oil into the flour with your hands.
Add the water and knead the dough, adding a little more warm water if needed.
The dough should be smooth and soft when fully kneaded. Cover the bowl and leave aside at room temperature for a couple of hours.
Making the samosas:
Boil or pressure cook the potatoes.
Once cooked, peel and dice, then set aside.
Heat the oil in a pan.
Add the ginger powder along with the rest of the spices and salt.
Cook for one minute.
Add the cooked potatoes and cook for a further 3-4 minutes.
Add the peas, and cook for another 2-4 minutes on a low heat.
Remove from the heat and let the mixture cool.
Divide the dough into 15 equally sized balls.
Roll out each ball into a circle, and cut each circle in half.
Brush the edges with warm water.
Make a cone from each semicircle and fill it with a tablespoon of the cooled filling.
Press and seal the open edges with your fingers.
Heat about 3 inches of oil in a deep wok or pan.
Fry the samosas until golden brown (around 4-5 minutes).
Remove and drain on paper towel to remove all excess oil, and serve hot with chutneys or chickpea salad.