Traditional German Food Berlin: Berliner Potato Soup

Berliner Kartoffelsuppe is a hearty potato soup associated with Berlin, made with potatoes, root vegetables, herbs and sausage. This home-style version builds a savory broth, then mashes some of the potatoes to thicken it while leaving plenty of tender pieces; regional and family versions vary in their vegetables, texture and choice of sausage.

Ingredients

1 tablespoon neutral oil (15 ml), such as canola or sunflower oil
1 medium yellow onion, about 1 cup diced (150 g)
1 medium leek, white and light-green parts only, about 1½ cups sliced (150 g)
1 small piece celeriac, peeled and diced, about 1 cup (120 g); or use 2 celery ribs, about 1 cup (100 g), for a milder, less earthy flavor
2 medium carrots, peeled and diced, about 1 cup (150 g)
2 pounds starchy potatoes, peeled and cut into ¾-inch pieces (900 g); russets or floury yellow potatoes work well
6 cups unsalted or low-sodium chicken stock (1.4 L); vegetable stock is a suitable alternative
2 bay leaves
1 teaspoon dried marjoram (1 g), or 1 tablespoon chopped fresh marjoram (3 g)
½ teaspoon caraway seeds (1 g), lightly crushed, optional
1 teaspoon fine salt (6 g), plus more to taste; use less if your stock or sausage is salty
½ teaspoon freshly ground black pepper (1 g), plus more to taste
12 ounces fully cooked smoked bockwurst or similar German-style sausage, sliced into rounds (340 g); smoked kielbasa is a practical substitute, though its stronger garlic-and-smoke flavor changes the soup
⅓ cup heavy cream (80 ml), optional, for a softer, richer finish
2 tablespoons chopped flat-leaf parsley (8 g), for serving

Instructions

Prepare the vegetables. Dice the onion, leek, celeriac and carrots into small, fairly even pieces so they soften at a similar pace. Leeks can trap grit between their layers: slice them first, swish the pieces in a bowl of cold water, lift them out, and drain well. Peel the potatoes and cut them into roughly ¾-inch pieces. Keep the potatoes in a bowl of cold water if you need a few minutes before cooking, then drain them before they go into the pot.
Soften the aromatics. Set a large, heavy soup pot or Dutch oven over medium heat and add the oil. Stir in the onion, leek, celeriac and carrots. Cook for 7 to 8 minutes, stirring now and then, until the onion looks translucent and the vegetables begin to soften. Keep the heat moderate; browned or scorched leeks can make the broth taste harsh rather than gently sweet.
Add potatoes and broth. Stir in the drained potatoes, bay leaves, marjoram, caraway if using, salt and pepper. Pour in the stock and scrape the bottom of the pot to loosen any vegetables that have begun to stick. The liquid should mostly cover the vegetables. Bring it just to a boil, then reduce the heat to maintain a steady, gentle simmer.
Simmer until tender. Partially cover the pot and simmer for about 25 minutes, stirring once or twice. The soup is ready for the next step when a knife slides easily into the largest potato pieces and the carrots are tender. If the potatoes are still firm, simmer for another 3 to 5 minutes and check again; their size and variety affect the timing.
Thicken the soup. Remove and discard the bay leaves. Use a potato masher to mash about one-third of the potatoes and vegetables against the side of the pot, leaving the rest in distinct pieces. This gives the broth body without making the whole soup smooth. For a silkier texture, briefly blend one or two cups of soup in a heat-safe blender, taking care with hot liquid, then stir it back into the pot.
Heat the sausage. Stir in the sliced, fully cooked sausage and simmer gently for about 8 minutes, until it is hot throughout. Check a piece with a food thermometer; the USDA FSIS safe reheating temperature is 165°F (74°C). Avoid a hard boil, which can make sausage casings split and can break the potato pieces down further.
Finish and adjust. Stir in the cream, if using, and warm the soup for 1 to 2 minutes without letting it boil. Taste the broth and add salt or pepper as needed; stock and sausage vary considerably in saltiness. If it seems thicker than you like, add hot water or stock a little at a time. Stir in the parsley just before serving.

Tips

Clean the leek carefully. Grit settles between the layers and is unpleasant in an otherwise soft soup. Washing sliced leek in a bowl lets the dirt fall to the bottom; lifting the leek out is more effective than pouring the whole bowl through a strainer.
Choose potatoes for the texture you want. Russets and other floury potatoes mash readily and make a thicker broth. Waxy potatoes hold their shape better and give a brothier result. Either is appropriate for a rustic soup, so use what is available rather than overworking the pot to force a particular texture.
Use celeriac if you can find it. This knobby celery root is a familiar flavor in German soups, but it may be hard to locate. Regular celery is a good substitute; it tastes fresher and less earthy, so the finished soup will be a little lighter. Peel celeriac deeply to remove its rough outer skin.
Season in stages. Start with the measured salt, then taste after the sausage has heated. Smoked sausage and prepared stock can contribute plenty of salt, and reducing the broth concentrates it. If the soup becomes too salty, add unsalted stock or water and a few extra cooked potato pieces rather than trying to hide the salt with more herbs.

Serving Suggestions

Serve the soup hot in deep bowls, making sure each portion gets a fair share of sausage and vegetables. A slice of dense rye bread, crusty sourdough or a German-style dark bread is useful for dipping and makes the meal more substantial. A simple green salad with a lightly tart vinaigrette offers a fresh contrast to the soft potatoes and smoky sausage.

Set extra chopped parsley and black pepper on the table so everyone can finish a bowl to taste. If you want a traditional-feeling spread, serve small dishes of pickles or mustard alongside the bread. Their sharp, tangy flavors balance the richness without needing to alter the soup itself. This is a filling main-course soup, but smaller portions also work as a first course before roast meat or another hearty meal.

Variations

Make it meat-free: Use vegetable stock and omit the sausage. For a little more substance, add a drained 15-ounce can of white beans (about 425 g) during the last 5 minutes of simmering. The beans are not a direct substitute for smoked sausage, so add a pinch of extra marjoram and black pepper if you want a more pronounced savory flavor.

Use another sausage: Fully cooked bockwurst is a good fit, but a mild smoked sausage or kielbasa works when German sausage is unavailable. Kielbasa usually has a stronger garlic flavor. If using raw sausage instead of fully cooked sausage, cook it separately or in the soup until its center reaches 160°F (71°C) for ground pork sausage, checked with a food thermometer; do not rely on color alone.

Make the broth creamier: The optional cream softens the savory edges, but it is not essential. For a dairy-free bowl, leave it out and mash a little more potato into the broth. You can also replace the cream with a small splash of unsweetened oat cream, though that adds a mild cereal note.

Adjust the herbs: Marjoram gives the soup a characteristic warm, savory aroma. If you cannot find it, use half as much dried thyme; the flavor will be more woodsy and less specifically German in character. Fresh marjoram is delicate, so stir it in near the end rather than simmering it for the entire cooking time.

Storage and Reheating

Cool leftovers promptly and refrigerate them within 2 hours of cooking, in shallow, covered containers. Keep the soup refrigerated for 3 to 4 days. The potatoes absorb broth as the soup sits, so it will probably be thicker the next day; this is normal and easy to correct when reheating. For best texture, store the soup and any extra bread separately.

Reheat only the portion you plan to serve in a saucepan over medium-low heat, stirring regularly and adding a splash of water or stock until the broth loosens. Heat leftovers to 165°F (74°C), checking the center with a food thermometer. If reheating in a microwave, cover the bowl loosely, pause to stir partway through, and check the temperature in more than one spot. Avoid repeatedly cooling and reheating the entire pot.

For longer storage, freeze the soup in airtight, freezer-safe containers for up to 2 to 3 months for best quality. Leave a little room at the top for expansion. Potatoes can become somewhat grainy after freezing, and cream may separate, so freezing before adding cream gives a better result. Thaw in the refrigerator, reheat to 165°F (74°C), and stir well; add cream only after the soup is hot.

Frequently Asked Questions

What is Berliner Kartoffelsuppe?
It is a Berlin-associated potato soup made with potatoes, vegetables and herbs, often served with sausage. There is no single fixed household formula: some versions are chunkier, some are more thoroughly mashed, and the vegetables and sausage vary. This recipe keeps a rustic texture and uses celeriac, leek and marjoram for a savory broth.

Can I make the soup without a blender?
Yes. A handheld potato masher is enough to thicken it; mash some of the vegetables against the side of the pot and leave the rest intact. If you prefer a smoother soup, mash more of the potatoes. A blender is optional, and blending the entire pot can make potato soup sticky if it is processed too aggressively.

Can I prepare it ahead?
Yes. You can cook the soup a day ahead and refrigerate it promptly, then reheat it gently to 165°F (74°C). It often thickens overnight as the potatoes take up liquid, so have extra stock or water ready. For the freshest texture, add parsley after reheating, and add cream at the end if you are using it.

What can I use instead of celeriac?
Use an equal volume of diced celery. It is easier to find and works well in the broth, but its flavor is greener and milder than celeriac. If you want to add more earthy depth without celeriac, a small amount of extra carrot or a little chopped parsnip can help, though either changes the balance slightly.

Why did my potato soup become gluey?
Potatoes release starch when they are mashed or blended, and vigorous blending can make that starch turn the soup gummy. Mash only part of the vegetables for a rustic result, or use short pulses if blending a portion. If the soup is already very thick, thin it with warm stock and stir gently rather than continuing to blend it.

Is this soup meant to be served as a main dish?
It can be. The potatoes and sausage make a substantial bowl, especially with bread on the side. For a lighter course, serve smaller portions and reduce the amount of sausage in each bowl. If you leave out the sausage, beans or a side of bread can make the meal more filling without changing the basic method.

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