In a medium bowl, combine the warm water, dried yeast and caster sugar; stir gently and leave for 5–10 minutes until foamy.
In a large bowl, whisk together the plain flour and salt.
Pour in the yeast mixture and olive oil, then stir until a rough dough forms.
Turn the dough onto a lightly floured surface and knead for 5–7 minutes until smooth and elastic.
Lightly grease a clean bowl with olive oil, place the dough inside, turn to coat, cover and leave in a warm place for 60–90 minutes until doubled in size.
Meanwhile, make the tomato sauce: in a small bowl, stir together the tinned chopped tomatoes, minced garlic, dried oregano, dried basil, salt and black pepper.
About 30 minutes before the dough is ready, preheat the oven to 245°C (fan 225°C), gas mark 9, with a pizza stone or heavy baking sheet on the middle shelf.
Punch down the risen dough and turn it onto a lightly floured surface; roll or stretch into a 30–35 cm circle.
Transfer the dough to a piece of baking paper or a lightly floured pizza peel.
Spread the tomato sauce over the dough, leaving a 1 cm border around the edge.
Scatter the grated mozzarella evenly over the sauce, then arrange the pepperoni slices on top. Drizzle a little olive oil around the crust if you like.
Carefully slide the pizza (on the baking paper or peel) onto the preheated stone or baking sheet and bake for 12–18 minutes, until the crust is golden and the cheese is bubbling and lightly browned.
Remove the pizza from the oven and allow to rest for 2 minutes before slicing and serving.