Mix yeast with a quarter cup of warm water and sugar and leave aside until frothy. Add frothy yeast to refined flour. Add salt and oil and mix. Add water and knead into soft dough. Leave the dough covered with a damp cloth in a warm place for about forty five minutes or until the dough is about double in volume.
Knead the dough again and keep for ten to fifteen minutes more covered with a damp cloth. Divide pizza dough into four portions, roll out each portion into medium thick eight inch discs. Prick them with a fork all over.
Grease a baking tray with fat and place the pizza bases over it. Preheat the oven to 220°C. For the sauce heat olive oil in a non stick pan, add the onion and garlic and sauté for two minutes. Add the tomatoes and stir.
Add one cup of water and bring it to a boil. Stir in the basil leaves, salt and crushed red chillies. Simmer for about five minutes on medium heat or till it reaches a thick sauce consistency. Spread the sauce equally on all the pizza bases.
Spread half cup of grated cheese on equally on them and sprinkle dry oregano. Bake them in the preheated oven for eight to ten minutes or until the pizza bases are crisp.
Remove the pizzas from the oven and top them with tomatoes, green capsicum, onions and corn. Sprinkle crushed red chillies, the remaining grated cheese and olive oil. Tear the basil leaves and sprinkle on the pizzas.
Bake the pizzas again for few minutes until the cheese melts and starts bubbling. Remove from oven, cut each pizza into six or eight pieces and serve hot.