Turn the grill onto its highest setting and place a wire rack on the top shelf of the oven.
Lightly dust the top of one ball of dough with flour. preserving as many air bubbles as possible, stretch the dough out with your two hands very gently. Drape the dough over your left fist and using your right hand, stretch out the dough slightly. Rotate the dough and stretch again, working your way around the whole circle of dough until you have a nice thin circle with a slightly thicker circumference where the crust will be. Lay it down on a lightly floured surface.Place your largest cast iron skillet or oven-proof frying pan over a medium heat. When hot, add half of your semolina (this will stop the pizza sticking).
Working quickly, lift the stretched out dough and place it into the hot skillet (if it folds on itself, quickly straighten it out with your finger- reduce the heat to its lowest. Spread 4 tbsp of the tomato sauce onto the centre of the pizza and spread out with a spoon. Top with half of the garlic, capers, olives and roasted red peppers. Sprinkle with oregano, a pinch of salt and pepper and drizzle with a tbsp olive oil. If you like, brush the crust with olive oil using a pastry brush.
Place the skillet under the grill, making sure the pan is as close to the heating element as possible. Grill for around 2 minutes, checking regularly to make sure its not burning. The crust should puff up nicely and brown around the edges. The toppings should be piping hot. Remove from the oven and turn out onto a chopping board. Top with parsley, slice and serve.