1. Heat the olive oil in a small cooking pot and add the garlic until fragrant. Add onion and fry. Once the onion begins to colour lightly, add all other ingredients, tomato cans, sugar, black chocolate, salt, onion powder (optional) and pepper.
2. Bring it to a boil, then reduce the heat to low and simmer for about 15 min, stirring occasionally. Check the seasonings add more salt or pepper if required.
3. Store the sauce in a clean jar in the fridge until you use. The sauce also suitable to freeze if you don't use all of them.