Mix together the yeast, sugar and water together. Allow to activate for 5-10 minutes.
Put the flour and salt in a bowl, add the rest of the water and olive oil, then add the yeast mix. Mix to combine then knead until dough is smooth and elastic. Place in an oiled bowl, cover with a damp tea towel and allow to rise until double in size.
Roll into pizza shapes, place on an oiled tray and allow to rise a second time.
Spread the passata over the pizza bases. Arrange the tomato slices then the mozzarella around the pizzas. Bake for 7-10 minutes until cooked.