Peel garlic. Roughly cut onion into pieces. Puree canned tomatoes in a bowl.
In a pot, heat up margarine and garlic on a low heat until golden. Remove from the heat and set aside.
Use a small but deep and solid pan otherwise the marina sauce might burn later. In there heat up olive oil on a high heat and add half of the pureed tomatoes. Without stirring let them cook for 5 minutes. Add onion, cocktail tomatoes cut in half, salt and a shot of white wine. Stir until combined and let simmer for 5 minutes. on a medium heat. After that add tomatoes, margarine, garlic and pepper. In case the tomatoes are a bit too sour, add some sugar now. Let the covered sauce cook for 10 minutes.
Add basil and puree everything until smooth. Season with salt and pepper.