Mix salt and yeast together in a jug with the water. Place flour in a bowl, make a well in the centre and add the water mixture along with the oil. Use a wooden spoon to mix everything to create a wet dough. Put on floured surface and knead for 5 minutes.
Place in greased bowl and cover with tea towel. Leave at room temperature to rise for 30 minutes (should double in size).
Round into a pizza base and stab with fork several times.
Spread tomato puree over the base. Add chopped tomatoes on top then add onion and garlic. Sprinkle over cheese and arrange pepperoni. Season with salt and pepper and sprinkle on basil.
Place on oiled baking tray. Cook at 200 C / Gas 6 for 20 minutes.