Sautee the onions In a large Dutch oven or pot, over medium heat, melt the butter and add the oil. Add the onions and a pinch of salt and pepper. Stir and cook till soft. This will take about 5 to 8 minutes giving the onions a chance to bed the aromatics. Add the garlic, stir and cook them for about a minute, just enough time to marry the two.
Cook the tomatoes Add the tomatoes, salt, pepper, tomato paste and passata all at the same time and cook on medium to high heat.
Tomato water: Pour a 1 cup of water into the empty tomato can, give it a swirl and set it aside.
Spices: If you’re going to be adding any spices this would be a good time to add them with the tomatoes.
Tomato water: Pour the tomato water (from earlier), season a little more, add the stock and the sugar. Give it all a good mix. Cover the pot with lid at a slight slant and cook for 10 minutes. Add your choice of fresh herbs if using and your soup is ready for the blender.
Blend Pour the soup into a blender and blend until smooth.
Serving options: cream, crostini, fresh basil, a drizzle of olive oil and black pepper.