Tip the flour into a bowl, then stir in the yeast and 1 tsp salt. Make a well in the centre and pour in 200ml warm water (make sure it’s not too hot) along with the oil. Stir together with a wooden spoon until you have a soft, fairly wet dough.
Tip the dough out onto a lightly floured surface and knead for 5 mins until smooth. Cover with a tea towel and set aside for an hour or so or until the dough has puffed up and doubled in size. You can also leave the rough, unkneaded dough in the bowl, cover with a tea towel and leave in the fridge overnight and the dough will continue to prove on its own.
Meanwhile, make the tomato sauce. Put the oil in a small pan and fry the garlic briefly (don’t let it brown), then add the passata and simmer everything until the sauce thickens a little. Leave to cool.
Once the dough has risen, knead it quickly in the bowl to knock it back, then tip out onto a lightly floured surface and cut into two balls. Roll out each ball into a large teardrop that is very thin and about 25cm across (teardrop shapes fit baking sheets more easily than rounds).
Heat oven to 240C/220C fan/ gas 9 with a large baking sheet inside. Lift one of the bases onto another floured baking sheet. Smooth the sauce over the base with the back of a spoon, scatter over half the mozzarella, drizzle with olive oil and season. Put the pizza, still on its baking sheet, on top of the hot sheet in the oven and bake for 8-10 mins until crisp.