Sauté the Aromatics: Heat the olive oil in a large saucepan or Dutch oven over a medium heat. Add the finely chopped onion and a pinch of salt. Cook gently for 6-8 minutes, stirring occasionally, until the onion is soft, translucent, and sweet. You don't want it to brown, as this can add a bitter note.

Add the Garlic: Add the minced garlic and dried oregano to the pan and cook for another minute until fragrant. Be careful not to let the garlic burn.

Introduce the Tomatoes: Pour the two tins of plum tomatoes into the pot, juice and all. Use a wooden spoon to break up the whole tomatoes against the side of the pan.

Simmer to Develop Flavour: Pour in the vegetable stock and add the caster sugar (if using). Bring the mixture to a gentle simmer. Once simmering, reduce the heat to low, tear in the fresh basil leaves, cover the pan, and let it cook for 15 minutes. This allows the flavours to meld together.

Blend the Soup: After 15 minutes, remove the soup from the heat. What works best for me is using an immersion (stick) blender to blitz the soup directly in the pot until it's completely smooth. This saves on washing up! If you don't have one, carefully transfer the soup in batches to a stand blender and blend until smooth, then return it to the pot.

Add the Cream: Place the pot back on a very low heat. Slowly stir in the double cream. Heat the bisque gently for a minute or two, but do not let it boil, as this can cause the cream to split.

Season and Serve: Taste the bisque and season generously with salt and freshly ground black pepper. Ladle into warm bowls, garnish with a few small basil leaves and an extra swirl of cream if you like, and serve immediately.