Sift flour and salt into a bowl, make a well in the center and add water. Mix to a firm dough and knead for 5 minutes until elastic, dusting with more flour if necessary. Wrap in plastic film and leave to rest for 30 minutes.
Cut most of the green tops from leeks, halve lengthwise and rinse well to remove all traces of soil between leaves. Remove roots and dry leeks with paper towels. Place flat on board, cut along length at 5 millimeter / 1/4 inch intervals then across to dice. Measure in cup measure and place in bowl. Add salt and chili pepper and knead with hand to soften leeks. Stir in oil.
Roll pieces of dough into balls the size of a large hazelnut and roll thinly into a 10 centimeter / 4 inch circle. Alternatively roll out dough and cut into 10 centimeter / 4 inch rounds.
Place about 2 teaspoons leek filling in center of circle, moisten pastry half way round edge of circle and fold pastry over filling. Press edge to seal well, and using the edge of a thimble, (the traditional method) or a coffee spoon make little crescent-shaped marks around the edge, or press with fork.
Fry 3 or 4 at a time in hot oil until golden brown, turning to brown evenly. Drain on paper towels and serve hot or warm.