1. Combine the yeast with the water, salt and sugar in a bowl. Stir, cover with a wet tea towel or cling film and leave to sit in a warm environment for 10 minutes. Note that bubbles will appear on the surface.
2. Sift the flour into a large bowl. Add the yeast mixture to the flour and 2tbsp olive oil. Mix until it comes together then turn it out onto a clean and floured surface.
3. Knead for 5-10 minutes, until smooth and elastic. Divide the dough in quarters and place the four portions onto a greased baking tray. Cover with a clean damp tea towel and leave for 30 minutes.
4. Once the dough has doubled in size, take each piece and roll out on a floured surface to a rectangle approximately 0.25cm thick.
5. Place 50g spinach on half of the dough rectangle, leaving 1cm around the edge free for sealing.
6. Crumble ¼ of the feta on top of the spinach. Season with cracked black pepper.
7. Fold the top half of the dough over the filling and press the edges together to seal.
8. Heat oil in a frying pan and once hot, place the gozleme in the pan and fry for 2-3 minutes on each side. Alternatively you can do this on a BBQ hot plate.
9. Serve immediately with lemon wedges and rock salt.