Peel and finely dice the onion and garlic. Heat the oil in a large pot. Fry the onion and garlic for about 5 minutes while stirring. Add the tomatoes and chop with a spatula.
Bring to the boil and simmer for about 30-40 minutes until slightly thick (be careful - the sauce will splash!).
Crumble the herbs into the sauce with your fingers after about 20 minutes. Season to taste with salt, pepper and sugar.