Mix the yeast and 250ml warm water in a small bowl, and leave to stand for 5-10 mins until foamy – this means the yeast is working. Put the flour and salt in a large mixing bowl (or use a tabletop mixer fitted with a dough hook and set at a low speed). Add the yeast mixture and mix by hand or machine until the dough comes together into a ball. If the mixture is too sticky to form a ball, add 2 tbsp flour and mix again. Knead for 12 mins by hand, or 8-10 mins on a high speed in the mixer, until smooth, then put in a lightly oiled bowl. Turn to coat the dough in the oil, cover with cling film and leave in a warm place for 2-4 hrs until doubled in size. (You can also put it in the fridge overnight, punch down and let it rise again at room temperature.)
Heat the oven to 240C/220C/gas 9. Put a baking sheet or pizza stone on the middle shelf. If you’re using lamb leg meat, blitz it in a food processor until it’s finely minced. Heat the olive oil in a large frying pan over a medium-high heat until hot. Add the onion and garlic, and cook for 10 mins until golden. Add the lamb and cook for 5 mins or until brown, breaking up any lumps with a spoon, then pour off any excess oil. Add the spices, some seasoning, tomato purée, tomatoes and the pomegranate molasses, and cook for 5 mins more, mixing everything together well and breaking down the tomatoes with a spoon. Remove from the heat and leave to cool completely. Can be done one or two days ahead.
Roll out the dough on a floured surface into a large rectangle about 30 x 40cm. Sprinkle 1 tsp or so of the semolina on a baking sheet. Put the dough on top and make sure it can move around. Add the spicy lamb first, then top with the red onions, pine nuts and feta. Slide onto the heated baking sheet or pizza stone and cook for 10-15 mins until crisp on the bottom.
Remove and drizzle with a little extra pomegranate molasses, then scatter over the parsley and pomegranate seeds. Transfer to a large board and cut into diamonds to serve.