Place the flour in a large bowl and add the yeast to one side and the salt and sugar to the other. Mix everything together and make a well in the centre, add the olive oil and water. Stir together to form a rough dough; add a drop more water if it seems dry.
Turn the dough out onto an un-floured surface and knead for about 10 minutes until smooth and elastic. It should be a little sticky at first but become smooth as you knead. You can also knead it in a stand mixer on medium speed.
Place the dough in a lightly oiled bowl, cover, and set aside to rise for an hour or two until doubled in size. Alternatively, you can place the bowl in the fridge for up to a couple of days.
While the dough is rising prepare the tomato sauce. Heat the olive oil in a pan and add the onion. Cook gently for about 10 minutes until softened.
Add the garlic and tomato puree and cook for another minute or two. Add the tinned tomatoes, oregano, sugar and chilli flakes. Simmer for about 20 minutes until it has reduced down to a thick sauce.
Add the basil and season to taste with salt and pepper. If you prefer a smoother sauce, you can use a potato masher to break down the tomatoes.
Preheat the oven to 240°C/220°C fan/475°F/gas mark 9. Line two baking sheets with baking parchment and sprinkle with semolina.
Punch down the risen dough, divide it into two pieces and roll into balls. Dust a work surface with flour and semolina.
Either use a rolling pin to roll out one of the balls of dough, or use your hands to stretch it into a circle about 23-25 cm wide. Try to make it slightly thicker around the outer edge so that you have a nice crust.
Repeat with the other ball of dough and place each one on one of the baking sheets.
Spread a thin layer of the tomato sauce over each pizza base. lay slices of the mozzarella on top, then the pepperoni slices. Brush the pepperoni with a little olive oil. Sprinkle with chilli flakes, dried oregano and black pepper.
Bake for 12-15 minutes until golden brown, crispy round the edges and cooked through.
Notes
See post above for tips, details and step-by-step photos.