Potato soup is not something that usually gets associated with spices or other strong flavors. Typically, it is grouped with hearty foods rather than with those that have complex flavor profiles. That said, it can be greatly improved with the right seasonings Here are some of the best spices for potato soup.
Leek
Leeks have a mild savory, vegetal flavor similar to that of onion but subtler. Leeks are traditional ingredients in potato soup and help to provide one of the layers of complex flavors that can take this soup from bland and starchy to deeply flavorful.
Unlike onions, leeks have to be cooked to be rendered tender enough to eat. Its mildness allows you to use it like a vegetable as well as a seasoning. Not only does it help to season your potato soup, but it also provides a green element and a nutritional boost to the dish.
Onion
A universal favorite seasoning vegetable, onions will enhance your potato soup just like leeks but will provide a more assertive version of the same flavor. Onions are pungently savory with an almost aggressive grassiness that will help your potato soup to feel like a complete dish instead of wet mashed potatoes.
Ideally, you should add onions to your potato soup at different points in the dish’s cooking process. Start the soup off with some of your onions then add some more at the midpoint and then finish up with a third batch at the end of the cooking time. This layers the onion flavor so you get the sweetness from the onions that cooked longest with a more intense flavor from the recently added onions.
Bacon
One way that many cooks add the umami character to their potato soup is with bacon. Bacon provides juices and fat that renders off into the soup adding smokiness, saltiness, and a strong meaty flavor.
One popular way to use it is to start by frying chopped bacon and then adding the other ingredients gradually. The bacon fat will also give the soup a rich, unctuous quality that it may lack without it.
Parsley
A mildly bitter herbal note can complement your potato soup, and you can get that note from parsley. Parsley gives potato soup color along with its flavor. A light sprinkling of parsley right before serving your soup will add a little brightness as well as some green color for contrast.
You can use dried parsley instead of fresh, but the flavor won’t be as strong and the color will be darker and duller. Curly parsley and Italian parsley will provide similar benefits.
Celery
Another important herb, celery shows up in many potato soup recipes. It is an important source of umami in addition to providing its own distinctive herbaceous flavor. Because of its aromatic properties, it can be beneficial to add chopped celery at various points in the cooking process to layer its flavor like the onions above.
Celery is sometimes cooked with aromatics and bacon early on but you can also add it a few minutes before the dish is served.
Cheddar cheese
While it is technically not a spice, cheddar cheese is a valuable seasoning that does show up in some British potato soup variants. It adds richness to the soup along with its tangy, cheesy flavor. It also lends a strong savory property to the soup.