Asparagus has an assertive flavor, but it’s nicely tempered in a soup. Potatoes and asparagus work well together and they make a perfect pair. When buying asparagus, settle on stalks that are medium in width. If the stalks are a little too thick-stemmed, peel them. Otherwise, the stems are quite tasty, so leave them in the soup. Although you can find asparagus year round, I’d wait until spring to make this, when asparagus are young and sweet.