To make the dough, place the yeast, sugar and water in a small bowl and mix to combine. Set aside in a warm place for 5 minutes or until bubbles appear on the surface.
Place the flour and salt in a large bowl and make a well in the centre. Add the yeast mixture and oil stirring with a butter knife until a dough forms. Turn out onto a lightly floured surface and knead for 5 minutes or until smooth and elastic.
Place the dough in a large bowl, cover with a damp cloth and set aside for 30 minutes or until the dough is doubled in size.
Preheat the oven to 230oC/450oF/Gas 5.
For the topping, place the tomatoes, oregano, salt and pepper in a bowl and crush with a potato masher. Divide the dough into four and roll out each portion to a 14cm/5.5 inch round. Place on greasy baking trays and top each pizza with mozzarella, parmesan, bocconcini and tomato mixture and cook for 10-15 minutes or until golden and crispy.