Easy Creamy Potato, Leek, and Sauerkraut Soup

I have written about my mom’s hot dog and cabbage soup, one of my favorites from childhood. It’s comforting and simple, and as it turns out, is a riff on a classic Polish soup called kapusniak. Here’s a second version I developed.

The idea for making the second version of the soup creamy came to me, indirectly, from my wife, who has a serious thing for creamy soups. As it happens, potato-leek soup is one of my all-time favorites. (And, in fact, the very first recipe of my own devising that a chef allowed me to put on a public-facing menu!) In my version of the soup, I cut the classic milk and cream base with buttermilk, which adds some acidity and brightness to a soup that I otherwise find a bit too starch-on-fat heavy. With the array of ingredients I had in front of me, I wondered: What would happen if, instead of buttermilk for acid, I used a good amount of sauerkraut?

I started by sautéing sliced kielbasa in a little vegetable oil until it was nicely browned. I then removed it from the pan and saved it to use later as a garnish, leaving that kielbasa fat in the pan to add flavor to the soup. Next, I added plenty of butter and leeks, reducing the heat to allow the leeks to gently soften without getting any color on them. (The sweetness of caramelized alliums was not what I was after in this dish.) Once they were properly softened, I added chicken stock, sliced cabbage, and bay leaves. Though I typically use russet potatoes for my potato-leek soup, I found the creamier texture of Yukon Golds worked better here.

On my first attempt, I immediately dumped in a full pound of sauerkraut with its liquid. Bad idea. As it turns out, acid can inhibit the breakdown of pectin, the carbohydrate glue that holds plant cells together. In the tart liquid provided by the sauerkraut, my potato chunks never softened. I had to fish them out and replace them with potato chunks I had cooked separately in boiling water.

The way to do it instead is to simmer the soup until the potatoes are completely softened, then add the sauerkraut and its liquid.

Once it comes back up to a simmer, it's ready to hit the blender. Some soups can be blended directly in the pot. Not this one. Even with the winner of our hand blender testing at my service, the soup remained unappetizingly chunky. A spin in the countertop blender and a pass through a fine-mesh strainer are necessary for a silky-smooth texture.

To serve the soup, I add back some of the browned kielbasa slices and garnish the whole thing with chopped fresh dill and a few drops of really great olive oil.