Dissolve the yeast and sugar in 125 ml of the warm water and set aside in a warm place for about 10 minutes until frothy. Use your fingers to work 90g of the flour into the yeast to make a sloppy paste. Sprinkle lightly with a little more flour, then cover with a tea towel and set aside in a warm place for 30 minutes to form a ‘sponge’.
Put the remaining flour and the salt into a large bowl. Make a well in the centre and add the sponge, oil and remaining water. Use your fingers to work it to a soft, sloppy dough. Don’t panic: it is meant to be very sticky!
Transfer to an electric mixer fitted with a dough hook and knead on a low speed for 10–15 minutes until very smooth and springy. Transfer to a lightly oiled bowl, then cover with a damp tea towel and leave to rest at room temperature for 1 hour or until doubled in size. (From this point you can proceed to bake the pide bread or filled pide boats. You can also refrigerate the dough until you are ready to use it. It will keep for around 24 hours, but take it out of the refrigerator a good 3 hours before you want to use it, to give it time to return to room temperature slowly.).
When ready to bake the bread, preheat the oven to its highest setting with two pizza stones or oiled baking sheets in it. Divide the dough in two, then form into rounds and leave, covered, to rest for 30 minutes. Mix the egg and milk to make an egg wash. Place the dough on a lightly floured work surface. Use the heels of your hands to press and flatten each piece of dough out to a 20 cm oval.
Brush the surface liberally with the egg wash. Dip your fingertips into the egg wash and mark rows of deep indentations across and down the length of the dough, leaving a narrow border. Now comes the tricky bit. Lightly flour the hot pizza stones or trays. Lift on the pides, stretching them gently and evenly. Sprinkle with nigella or sesame seeds and bake for 8–10 minutes until crisp and golden brown.