Delia Smith potato and leek soup is the one I reach for when I want something warm, cheap and made in a single pan. Strictly, her official title is Leek, Onion and Potato Soup. It comes from The Delia Collection: Soup and Delia’s Vegetarian Collection, and I checked every quantity below against the recipe on her Delia Online site.
The method is simple, but the page leaves a few things unsaid. The 35 minutes it lists is cooking time only. “Serves 4 to 6” is a wide gap. And there is no advice on how long the soup keeps or whether it freezes. I cover all three below, with the maths shown.
Jump to the recipe card at the end of this page for exact quantities and a printable version.
What’s in It
Leeks do most of the work, with a smaller amount of potato and one onion. They sweat slowly in butter, then simmer in vegetable stock and a little milk. At the end the soup is blended smooth and finished with cream or crème fraîche, plus chives or parsley. You need a large, thick-based saucepan with a lid, a wooden spoon, a sharp knife, and a blender or stick blender.
Potato and Leek, or Leek and Potato?
People search for it both ways, and plenty of sites call it leek and potato soup. Delia’s own title is Leek, Onion and Potato Soup. It is the same soup. The onion is part of her version, so keep it in if you want to follow her recipe. Her page also says that the chilled version is a classic vichyssoise.
Is This Really Delia’s Recipe?
Yes. The quantities in my recipe card match her official page, which names two books as the source: The Delia Collection: Soup and Delia’s Vegetarian Collection. Some blogs change it. A few use chicken stock, one uses olive oil, and others leave the soup chunky. Those are fine changes, but they are not her recipe. I have no connection with Delia Smith or her team. I simply followed her published method.
Choosing Your Leeks and Potatoes
Pick firm leeks with plenty of white and pale green. “Large” means thick, so buy four fat leeks rather than six thin ones. Trim the roots and the tough outer layer, as Delia says. If the tops are very dark and coarse, I keep them for stock instead.
Delia only says “medium potatoes”. My pick is an all-rounder such as Maris Piper. It breaks down enough to thicken the soup without turning gluey. Very waxy potatoes hold their shape and thicken less.
How I Make It
- Prep the leeks. Trim the roots and the tough outer layer. Split the leeks in half lengthways and slice them quite finely. Then wash them in two or three changes of water and drain well. Washing after slicing lets the water reach the grit between the layers.
- Chop the rest. Chop the onion small. Peel the potatoes and dice them into pieces of a similar size, so they cook at the same speed. There is no oven, so there is nothing to preheat. This all happens on the hob.
- Melt the butter. Gently melt 50g of butter in a large, thick-based saucepan. Keep the heat low. The butter should melt, not brown.
- Sweat the vegetables. Add the leeks, onion and potatoes. Stir with a wooden spoon until everything has a coat of butter. Season with salt and pepper, put the lid on, and cook over a very low heat for about 15 minutes. The vegetables should soften and wilt without taking on any colour. Covered, they cook in their own steam, which keeps them sweet.
- Add the stock and milk. Pour in 850ml of vegetable stock and 275ml of milk. Bring it up to simmering point.
- Simmer very gently. Cover and simmer for 20 minutes, until the vegetables are soft. A piece of potato should squash easily against the side of the pan. Keep the heat low, because the milk can boil over if the pan gets too hot.
- Let it cool a little. Take the pan off the heat and wait a few minutes. Hot soup in a blender is a splashing risk.
- Blend until smooth. Fill the blender no more than halfway and work in batches, with a bowl ready for the first batch. A stick blender in the pan also works. Blend until just smooth and stop there.
- Reheat and season. Return the soup to the pan and warm it gently. Taste it and adjust the salt and pepper.
- Finish and serve. Swirl in a little cream or crème fraîche and scatter over snipped chives or chopped parsley.
The Serving Size Nobody Explains
Delia’s page says the soup serves 4 to 6. Other pages say 5. Here is what those numbers mean in bowls. The stock and milk add up to 1,125ml (850ml plus 275ml). That is before you count the vegetables, which add more volume once blended. So the pot makes a little over a litre at the very least.
I worked this out by dividing. Four servings is about 280ml each, and six servings is about 190ml each. Treat both as minimums. In practice, four servings gives you big supper bowls to eat with bread. Six gives you smaller starter portions.
The same split changes the calories. My estimate, using standard nutrition data and my own weights for the vegetables, is about 316 calories a bowl at four servings and about 210 at six. Both include the cream. The recipe card shows how I worked it out.
The Timing Nobody Mentions
The page lists 35 minutes. That figure comes straight from the method: 15 minutes of sweating plus 20 minutes of simmering. It leaves out the trimming, washing and slicing of the leeks, the dicing, and the cooling and blending at the end.
Some pages promise the soup in under 35 minutes. That cannot be right, because the cooking alone takes 35. My own plan is about an hour in total: roughly 15 minutes of prep, 35 of cooking, and 10 to cool and blend. That is my estimate, so allow a little more if your knife skills are slow or you are blending in several batches.
A Scaling Table for Smaller and Bigger Pots
If you are cooking for two or three, or filling the freezer, this table scales the recipe. The pan sizes are my own reasoning from the liquid and vegetable volume, not figures from Delia.
For the double batch, blend in more batches and expect it to take longer to come up to a simmer. I would keep the sweating and simmering times the same and check by squashing a piece of potato.
Common Mistakes and How I Fixed Them
Gritty soup
Cause: soil hides between the layers of the leeks, and washing them whole does not reach it. Fix: slice first, wash in two or three changes of water, and lift the leeks out of the water rather than pouring it away through them. The grit stays in the bottom of the bowl.
The milk boiled over
Cause: the heat was too high. Milk proteins and fat form a skin that traps steam, so it rises fast. Fix: turn the heat down to a very gentle simmer and stay close to the pan once the milk goes in. Delia warns about this in her method.
Dull, browned vegetables
Cause: the sweating stage was too hot, so the leeks fried instead of softening. Fix: use the lowest heat, keep the lid on, and give the pan a stir now and then.
Gluey soup
Cause: too much potato, or blending for too long, which can turn the starch sticky. Fix: keep to two medium potatoes and blend only until the soup looks smooth.
Bland soup
Cause: stock saltiness varies a lot between brands, so the same recipe can taste different each time. Fix: season at the end, in small pinches, and taste after each one.
Hot soup splashing from the blender
Cause: steam expands fast in a closed jug. Fix: let the soup cool a little, fill the jug no more than halfway, and hold a cloth over the lid.
Variations and Substitutions
- Vegetarian: Delia’s page labels the soup vegetarian, which works because it uses vegetable stock. Chicken stock would make it a meat soup.
- Gluten free: the recipe has no flour, but whether it is gluten free depends on your stock. Check the label.
- Dairy free or vegan: swap the butter for olive oil, the milk for a plant milk, and leave out the cream. This is my suggestion, not Delia’s, and the soup will taste a little different.
- Chunky: blend only half the soup and stir it back into the pan.
- Chilled (vichyssoise): chill the soup for several hours, then taste again. Cold food tastes less salty, so add salt in tiny pinches before serving.
What to Serve With It
Crusty bread and butter is the obvious partner. Cheese on toast also works well and turns a bowl of soup into supper. For a lighter meal, serve it as a starter before a simple main. Croutons or crisp bacon on top add crunch, though bacon makes it non-vegetarian.
Make Ahead, Storing and Freezing
Make ahead: you can cook the soup through to the blending stage, cool it, and keep it covered in the fridge. Reheat it gently, then add the cream when you serve.
Fridge: cool the soup quickly, ideally within one to two hours, then cover it and chill it. The Food Standards Agency advises eating leftovers within two days. Some recipe sites say three days for leek and potato soup. I go with the two days, because that is the official UK guidance.
Freezer: freeze the soup in portions, without the cream, for up to three months. Several leek and potato soup recipes give this time, and they also suggest holding dairy back. The soup already has milk in it, so it can look slightly grainy once thawed. A quick whisk or a go with the stick blender fixes that. Thaw in the fridge overnight and reheat until piping hot. Eat it within 24 hours of defrosting and do not refreeze it.
FAQs
How many does Delia Smith’s leek and potato soup serve?
Her page says 4 to 6. Four gives you big supper bowls of about 280ml each, and six gives you starter portions of about 190ml each. Those figures are my own division of the stock and milk, so the real amounts are a bit higher.
Is it vegetarian or gluten free?
It is vegetarian when you use vegetable stock, and her page labels it that way. It is not vegan, because of the butter, milk and cream. It has no flour, but check your stock label for gluten.
Can I make it without a blender?
Yes. You can mash the soup with a potato masher for a rustic texture, or press it through a sieve. It will not be as silky as a blended soup.
Can I freeze it?
Yes, for up to three months. Freeze it before adding the cream, thaw it in the fridge, and reheat it until piping hot.
Can I serve it cold?
Yes. Delia’s page says the chilled version is a classic vichyssoise. Chill it for several hours and check the seasoning again before serving.
Why does my soup taste bland?
Usually it needs more salt, or your stock is mild. Add salt in small pinches at the end and taste as you go.
Can I use the green parts of the leeks?
Delia only says to discard the tough outer layer, so a little pale green is fine. I would keep very dark, coarse tops for making stock.
Can I use chicken stock instead?
You can, and some online versions do. It changes the flavour a little and means the soup is no longer vegetarian. Delia’s official page uses vegetable stock.
One Last Thing
This is a simple soup that rewards slow, gentle cooking. Take your time with the sweating, keep the heat low once the milk goes in, and season at the end. Make a double batch if you have a big enough pan, because it freezes well.
Delia Smith Potato and Leek Soup (Leek, Onion and Potato Soup)
Ingredients
Equipment
Method
- Prep leeks. Trim the roots and tough outer layer. Halve the leeks lengthways, slice finely, wash in two or three changes of water and drain well.
- Chop vegetables. Chop the onion small. Peel and dice the potatoes.
- Melt butter. Gently melt the butter in a large, thick-based saucepan.
- Sweat vegetables. Add the leeks, onion and potatoes and stir to coat in butter. Season, cover and cook over a very low heat for about 15 minutes.
- Add liquid. Pour in the stock and milk and bring to a simmering point.
- Simmer gently. Cover and simmer very gently for 20 minutes until the vegetables are soft. Keep the heat low so the milk does not boil over.
- Cool slightly. Take the pan off the heat and leave it for a few minutes.
- Blend soup. Blend until smooth, filling the blender no more than halfway and working in batches if needed.
- Reheat and season. Return the soup to the pan, warm it gently and adjust the seasoning.
- Garnish and serve. Swirl in the cream or crème fraîche and scatter over the chives or parsley.
Notes
- No oven is used, so no fan oven or gas mark conversion applies. Use a very low hob heat for sweating and a gentle simmer after the milk goes in.
- Use a pan of at least 3 litres. The stock and milk alone come to 1,125ml (my arithmetic), and the vegetables add more.
- The 35 minutes on the original page is cooking time only. Plan about an hour in total, which is my estimate.
- Fridge: cool within 1 to 2 hours and eat within 2 days (Food Standards Agency advice). Freezer: up to 3 months, without the cream. Eat within 24 hours of defrosting and do not refreeze.
- Slice the leeks first, then wash them in several changes of water. Blend only until smooth, because over-blending potato can make it gluey.
- Vegetarian when made with vegetable stock. Check your stock label if you need it gluten free.
Tried This Potato and Leek Soup? I’d Love to Hear From You!
If you made this Delia Smith Potato and Leek Soup Recipe, I’d love to know how it turned out! Did you keep it classic or add your own little twist?
⭐ Leave a star rating if you enjoyed the recipe, and share your experience in the comments below. Your feedback helps other home cooks and means so much to me here at Cooking Picks.
Happy cooking!
Leave a Reply