What you need:
Tomato - 4 large, juicy ones
Onion - 1, chopped fine
Garlic - a few cloves
Oil - 1 tbsp
Salt - to taste
Sugar - a little
Heat oil in a pan. On a low flame, saute the onions until pink. Crush the garlic slightly and stir it in. Add chopped tomatoes, cover and cook for 8-10 minutes on low flame. Crush the tomatoes with a ladle. Add salt, sugar and a cup of water. Let it simmer for 15-20 minutes or until the sauce thickens.
This is the sauce that we used on our pizza. We kept it simple and non-spicy because that's how my daughter prefers it. However, this can be spiced up with some chillies or chilli powder. You could also add your favorite herbs to make it more flavorful.