Leek and potato soup is silky and sweet when you get three things right: sweat the leeks slowly so they soften without browning, use a potato that thickens without going gummy, and blend only until smooth. That is the whole method behind this Gordon Ramsay-style version, and it takes under an hour with nothing more than leeks, onion, butter, potatoes, stock and a little cream.
In keeping with Ramsay's rule to get organized first, have everything prepped before the butter melts: leeks sliced and washed, onion chopped, potatoes peeled and diced into even pieces so they cook at the same rate.
Wash Leeks After You Slice Them
Leeks grow with soil pushed up around their stems, and it works its way down between the layers. University of Illinois Extension advises using the white and light green parts, saving the dark green tops for stock, and rinsing well because of the soil caught between the layers. The easiest way is to slice first, then drop the slices into a big bowl of cold water and swish them around. The grit sinks, the leeks float. Lift them out with your hands or a slotted spoon rather than pouring the bowl through a colander, which tips the grit straight back over them.
Sweat the Leeks, Don't Brown Them
Sweating means cooking the leeks gently in butter, with a pinch of salt and the lid on, until they collapse and turn glossy and translucent, about 10 to 12 minutes. The heat breaks down the pectin that holds the leeks' cell walls together, so they soften and release their sweetness, and the salt helps pull moisture out. What you want to avoid is color. Browning is the Maillard reaction, and it only starts once the surface passes about 284°F; with the lid on and the leeks' own moisture in the pan, the temperature stays near 212°F, so they soften without browning. Brown leeks add a roasted, slightly bitter edge and turn the soup a muddy beige instead of pale green.
Why Yukon Gold Potatoes
The potatoes are what thicken this soup, so the variety matters. As they simmer, their starch granules absorb water and swell, which is gelatinization, and it starts around 150°F; that released starch gives the soup its body without any flour. University of Minnesota Extension notes that all-purpose potatoes like Yukon Gold have a balance of waxy and mealy starches, while waxy potatoes can become sticky when mashed. Yukon Golds give a creamy, buttery soup; starchy russets also work but can make it slightly grainy. Simmer until a piece crushes easily against the side of the pot, 15 to 20 minutes.
How to Blend It So It Doesn't Turn Gluey
Gluey potato soup is an overworked soup. Cooked potato starch sits inside swollen granules, and hammering it in a blender ruptures them and releases the starch, which turns the texture sticky and elastic, the same thing that happens to overworked mash. Blend only until smooth and stop. A stick blender in the pot, off the heat, gives you the most control. If you use a countertop blender, work in batches, fill it no more than a third full, and hold the lid down with a folded towel with the center cap removed: hot liquid releases steam as it spins and can force the lid off.
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Adding Cream Without It Splitting
Stir the cream in at the end over low heat and do not let the soup boil again. Heavy cream is stable in hot soup because of its fat: dairy with more than about 25% fat resists curdling, while lower-fat dairy can split when boiled, especially with salt or acid in the pot. Whole milk works for a lighter soup, but warm it through gently rather than boiling. Taste and adjust the salt last, once the cream is in.
Serve It Hot, or Cold as Vichyssoise
Chilled and enriched with cream, this same soup is vichyssoise. If you serve it cold, season it a little more than you think: taste is strongest at around body temperature, and cold food reads as blander, so a soup seasoned perfectly hot tastes flat straight from the fridge. Either way, top it with snipped chives, a swirl of cream and cracked black pepper, with crusty bread on the side.
Leftovers keep three to four days in the fridge, per USDA leftovers guidance. For freezing, freeze it before adding the cream. Potato starch firms up and can turn slightly grainy after freezing, and a quick blend when it is reheated brings it back.
The Smoked Haddock Variation
Add smoked fish and this becomes close to Scotland's Cullen skink. Poach about a pound of smoked haddock gently in 2 cups of milk until it flakes, around 5 minutes, since fish is done at about 140°F in the center. Lift it out, use the milk in place of some of the stock, blend the soup, then fold the flaked fish back in without blending. For more soups in the same spirit, try our French onion soup or the velvety pumpkin soup, and if you are shopping for a blender that can handle hot soups, see our budget blender picks.
Gordon Ramsay-Style Leek and Potato Soup
Ingredients
- 3 large leeks, white and light green parts, sliced and washed (about 1 lb trimmed)
- 1 onion, chopped
- 3 Tbsp unsalted butter
- 2 garlic cloves, sliced
- 1 1/2 lb Yukon Gold potatoes, peeled and diced
- 4 cups chicken or vegetable stock
- 1 bay leaf
- 1/2 cup heavy cream, plus extra to serve
- Salt and white pepper, to taste
To serve
- Snipped chives, cracked black pepper and crusty bread
Instructions
- Slice the leeks, drop them into a large bowl of cold water, swish, and lift them out so the grit stays at the bottom. Drain well.
- Melt the butter in a large pot over medium-low heat. Add the leeks, onion and a pinch of salt, cover, and sweat 10 to 12 minutes, stirring now and then, until very soft and translucent with no color. Add the garlic for 1 minute.
- Add the potatoes, stock and bay leaf. Bring to a boil, then simmer gently 15 to 20 minutes, until the potatoes crush easily against the side of the pot.
- Remove the bay leaf. Take the pot off the heat and blend with a stick blender just until smooth; do not over-blend.
- Return to low heat, stir in the cream and warm through without boiling. Season with salt and white pepper, and thin with a little stock if needed.
- Serve topped with a swirl of cream, snipped chives and cracked black pepper, with crusty bread.
Notes
Leek and Potato Soup FAQs
The questions that come up most: why the soup turned gluey, which potatoes to use, whether it freezes, and how it differs from vichyssoise.
Why is my leek and potato soup gluey?
It was over-blended. Blending cooked potato too hard ruptures the swollen starch granules and releases starch that turns the soup sticky and elastic. Blend only until smooth, preferably with a stick blender off the heat, and stop.
What potatoes are best for leek and potato soup?
Yukon Gold. All-purpose potatoes like Yukon Gold have a balance of waxy and mealy starches, so they give a creamy, buttery soup that thickens well without going gummy. Russets work too but can be slightly grainy.
Should I brown the leeks?
No. Sweat them gently in butter with the lid on until soft and translucent. Browning adds a roasted, slightly bitter note and turns the soup a dull beige instead of pale green.
Can you freeze leek and potato soup?
Yes, ideally before adding the cream. Potato soups can turn slightly grainy after freezing, so give it a quick blend when you reheat it, then stir in the cream.
What is the difference between leek and potato soup and vichyssoise?
Vichyssoise is essentially leek and potato soup enriched with cream and served cold. Season a cold soup a little more, because cold food tastes blander than hot.
Can I use milk instead of cream?
Yes, for a lighter soup, but warm it through gently without boiling. Lower-fat dairy is more likely to split when boiled, while heavy cream is stable because of its higher fat content.
Which part of the leek do you use?
The white and light green parts. Save the tough dark green tops for making stock.
About the Author
John Siracusa is the founder of Hell’s Kitchen Recipes. He focuses on technique-first, reproducible home cooking and researches recipes & kitchen equipment from published food science and professional chef methods since 2016.