This classic, creamy, velvety smooth soup is made from a wonderful blend of gently sautéed and steamed leeks, potato and onion. It is a fabulous example of how 6 simple ingredients can come together so quickly to create a smooth and luxurious dish. This wonderfully versatile soup can be served hot, to warm you on a cold day, or cold, to cool you on a hot day. Either way, garnish with a swirl of extra cream, your choice of garnishes and some fresh bread.
Collect together your equipment (see Recipe Notes below) and ingredients. You will need a large cast iron casserole dish or saucepan.
Make the cartouche: place the lid or base of the pan you are cooking the soup in on baking parchment, draw around the edge and cut it out. Fold into quarters or eighths, cut off the pointed end to create a small circle in the centre of the cartouche. Unfold and scrunch the paper in a ball. (This helps to make the baking paper easier to use.) Flatten the cartouche – it is now ready to use.
Make the soup: prepare the onion and heat the butter in the pan over a medium heat. Cook the onion for 5 minutes, until translucent but not coloured. Stir from time to time.
Prepare the leek and potatoes as the onion cooks and then add to the pan. Cook for a further 5 minutes, over a low heat, ensuring they do not colour. Continue to stir from time to time.
Add ½ teaspoon salt and mix thoroughly. Cover with the cartouche and a lid. This will help the vegetables to steam and keep their colour. Cook on a low heat for 10 minutes until the vegetables are soft, but not coloured.
Remove 4 teaspoons of sautéed leeks, if using as a garnish. Set aside.
Remove the cartouche and add 500ml of stock. Stir and bring to a gentle simmer. Cook on low for 5 minutes or until the vegetables are soft. Do not overcook or you will lose the fresh flavour of the vegetables. Leave to sit for 15 minutes to cool a little.
Blend the soup:
- Either use an immersion stick blender to blend the soup in the casserole
- or blitz in a food processor or blender. Do this in batches to avoid spillage and be careful transferring the very hot liquid.
Pour everything back into a casserole/saucepan and bring the soup to a gentle simmer. Add the milk and/or cream until you get the consistency you are looking for. Taste and adjust seasoning, if necessary. The amount of extra seasoning will depend on what stock you are using and how well it has been seasoned.
To serve Leek and Potato Soup: serve hot with fresh bread in warmed soup bowls, drizzle over some cream and add your choice of garnishes.
To serve Vichyssoise: serve cold, from the fridge, in cooled soup bowls, drizzle over come cream and add your choice of garnishes. Delicious with some fresh bread.
Equipment:
Vegetable weight – the weights given in the recipe is for prepared vegetables. I.e. weighed after the vegetables have been trimmed and peeled
Cartouche – this is the traditional French way of preparing the soup and helps to preserve the colour of the leeks. You could miss this out and simply cook the vegetables in the stock, but you may lose some of the fresh flavour and the green will be much less vivid in colour. It will still taste great though!
Vichyssoise - when it is served cold, it is known as Vichyssoise and is often prepared with more cream than a hot Leek and Potato Soup. However, make both to suit your own palate. It is always the best way to cook!