For the base: mix together the flour yeast and salt in a mixing bowl. Make a well in the centre and pour in the water and oil. Mix to a soft, fairly wet dough.
Turn onto a lightly floured surface and knead for 5 minutes until smooth. Put into a lightly greased bowl, cover with a tea towel and leave to rise until doubled in size - about 1 hour.
Heat the oven to 200°C (180° fan) 400°F gas 6. Line a baking tray with non-stick baking paper.
Quickly knead the dough and roll out into a large round about 25 cm|10" in diameter. Place on the baking tray.
For the topping: heat half the oil in a frying pan and cook the pepper and onion until softened but not browned.
Mix together the pepper, onion, sweetcorn, tomatoes and herbs. Season to taste with salt and black pepper.
Brush the remaining oil over the pizza base and spoon on the pepper mixture. Add the cheese.
Bake for about 20 minutes until golden and bubbling. Garnish with rocket.