Delia Smith Leek and Potato Soup Recipe

This creamy leek and potato soup is made with butter-sweated leeks, onion, potatoes, stock and milk. The gentle sweating method draws out the natural sweetness of the vegetables, giving you a silky, pale green bowl of comfort. Ready in 35 minutes and serves 4–6.

I make this all through autumn and winter, using just a heavy-based saucepan and a stick blender. Delia’s original name for it is Leek, Onion and Potato Soup, and the chilled version is a classic vichyssoise.

Leek and Potato Soup Ingredients

• The Vegetables:
  • 4 large leeks, trimmed, washed and sliced (use the green parts too)
  • 1 medium onion, peeled and chopped small
  • 2 medium potatoes (floury variety such as Maris Piper), peeled and diced
• The Liquid and Fat:
  • 50g butter
  • 850ml vegetable stock or light chicken stock
  • 275ml milk
• The Seasoning and Garnish:
  • Salt and freshly milled black pepper
  • 2 tablespoons cream or crème fraîche (for swirling)
  • Fresh chives, snipped, or chopped fresh parsley (for garnish)

What You’ll Need to Make This Soup

You do not need specialist kit for this recipe. A large, heavy-based saucepan (such as a Le Creuset casserole or a ProCook stainless steel stockpot) distributes heat evenly for the sweating stage. A stick blender like the Braun MultiQuick makes light work of blending the soup right in the pan.

A sharp kitchen knife and a large chopping board are the only other essentials.

How To Make Leek and Potato Soup

1. Prep the leeks: Trim the root and tough dark tops off the leeks. Split them in half lengthways, slice into rings roughly 1cm thick. Wash thoroughly in two or three changes of water to remove any grit, then drain well.
2. Sweat the vegetables: Melt the butter in a large, thick-based saucepan (a Le Creuset or similar cast-iron pan holds heat evenly) over gentle heat. Add the sliced leeks, chopped onion and diced potatoes. Stir well to coat every piece in the butter.
3. Cover and soften: Put a tight-fitting lid on the pan. Let the vegetables sweat over very low heat for about 15 minutes. This draws out their natural juices without browning, creating a sweet flavour base. Shake the pan now and then to stop sticking.
4. Simmer gently: Pour in the stock and milk. Season with salt and pepper. Bring to a gentle simmer, not a rolling boil, or the milk may split. Half-cover with the lid and simmer for 20 minutes until the vegetables are completely soft.
5. Blend until smooth: Take the pan off the heat and let it cool slightly. Use a stick blender (a Braun MultiQuick works well) or a jug blender to blitz until silky smooth and a pale green colour.
6. Reheat and finish: Return the soup to a clean pan. Reheat gently and taste for seasoning. Leeks often need plenty of pepper.
7. Serve: Ladle into warm bowls. Swirl a teaspoon of cream or crème fraîche into the centre of each bowl and scatter with snipped chives or parsley.

What Makes This Leek and Potato Soup So Good?

• Use the green tops: Many recipes throw away the green part of the leek, but Delia uses the tender green sections too. This gives the soup its distinctive pale green colour and a stronger leek flavour.
• Do not rush the sweating: The 15-minute sweating stage softens the vegetables so they melt into the soup later. Skipping this step gives a watery, sharp-tasting result.
• Choose floury potatoes: A floury variety such as Maris Piper breaks down during cooking and thickens the soup naturally. No need for cornflour or any other thickener.
• Milk, not cream: Adding milk alongside the stock gives a creamy feel without the heaviness of double cream. It keeps the soup light enough for lunch but rich enough to satisfy.
• Do not over-blend: Blend just until smooth. Over-blending activates the starch in the potatoes and can make the soup gluey rather than silky.
• Serve it cold as vichyssoise: Delia notes that the chilled version of this soup is a classic vichyssoise. Let the blended soup cool completely, then chill in the fridge for at least 4 hours. Serve with a swirl of cream and chives.

What Goes Well with This Soup?

A basket of warm croutons fried in garlic butter is the classic topper. For a heartier meal, serve with a chunk of crusty wholemeal bread or a warm cheese scone. A rasher of crispy bacon crumbled over the top adds a salty kick that pairs well with the sweet leeks.

If you enjoy Delia’s soups, try her carrot and coriander soup for a bit of spice. Her cauliflower soup is another comforting winter favourite.

How Should You Store This Soup?

Let the soup cool completely before storing. It keeps in an airtight container in the fridge for up to 3 days. It will thicken as it sits, so add a splash of milk when reheating.

Reheat gently on the hob over medium heat. Do not let it boil hard.

This soup freezes well for up to 3 months in freezer bags or tubs. Thaw overnight in the fridge and whisk well when reheating.

Can You Make This Soup Vegan or Dairy-Free?

• Vegan version: Replace the butter with olive oil and use oat milk or another plant-based milk instead of dairy milk. Use vegetable stock. Skip the crème fraîche or use a plant-based alternative.
• Dairy-free version: Same swaps as vegan. The soup still thickens naturally from the potatoes, so no extra ingredients are needed.
• Slow cooker method: Sweat the vegetables in butter on the hob for 15 minutes first, then transfer to the slow cooker with the stock and milk. Cook on low for 4–6 hours. Blend at the end.

Nutrition Facts

• Calories: 220 kcal
• Fat: 12g
• Carbohydrates: 25g
• Protein: 6g

Nutrition information is estimated per serving.

Frequently Asked Questions

Is leek and potato soup healthy? Yes. This recipe uses milk rather than double cream, keeping it at around 220 kcal per serving with 6g of protein and 12g of fat.

Why did my leek and potato soup turn grey? Browning the vegetables before adding the liquid causes a dull colour. Sweat them gently in butter with the lid on so they soften without colouring.

Do I need a blender to make leek and potato soup? An immersion blender or jug blender both work. You can also push the cooked soup through a sieve for a smooth result without any blender at all.

Can I add other vegetables to this soup? Watercress, spinach, or peas work well stirred in before blending for extra colour. Delia’s carrot and leek soup is a good example of a similar base with different vegetables.

How does Delia Smith’s leek and potato soup compare to other versions? Delia uses milk instead of double cream and insists on including the green leek tops for stronger flavour. Her French onion soup uses the same slow-sweating technique.

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• Delia Smith Carrot and Coriander Soup Recipe
• Delia Smith Pumpkin Soup Recipe
• Delia Smith Celery Soup Recipe
• Delia Smith Vegetable Soup Recipe