In a bowl, combine the yeast, sugar and 375ml (13fl oz/1½cups) warm water and stir until dissolved. Leave in a draught-free place for 10 minutes, or until bubbles appear on the surface. The mixture should be frothy and slightly increased in volume. If your yeast doesn’t foam, it is dead, so you will have to discard it and start again. Process the flour, yeast mixture and oil in a food processor for 30 seconds, or until the mixture forms a ball.
Turn the dough onto a well-floured surface and knead until smooth and elastic. Place the dough in a lightly oiled bowl. Cover with plastic wrap and then a damp tea towel and leave in a draught-free place for 20 minutes, or until almost doubled in size. Punch down the dough and divide into 12 equal portions. Roll each portion into a 5mm (¼inch) thick round. Place on greased baking trays and brush well with water. Set aside to rise for 20 minutes.
Preheat the oven to 250°C (500°F/Gas 9). If the dough has dried, brush it again with water. Bake for 4–5 minutes. The pitta bread should be soft and pale, slightly swollen, and hollow inside.