POTATO-LEEK SOUP

POTATO-LEEK SOUP IS A STAPLE OF EUROPEAN peasant cooking. It is at once hearty and creamy because of the potatoes and lean because cream is rarely added. We had a number of questions. What kind of potatoes are best, and how should they should be cooked to keep them from disintegrating? How many leeks are necessary for good flavor? Should other alliums (onions and garlic) be added to the base?

We started by testing various kinds of potatoes. In our opinion, the potatoes in this soup should be tender but not mushy or waterlogged. In many of the recipes we tested, the potatoes fell apart into a starchy mess. Low-starch red potatoes are a must here. We discovered that they hold their shape better than russet potatoes or Yukon golds.

Precise timing for cooking the potatoes was hard to pinpoint. One minute the potatoes tasted a bit underdone, the next minute they were too soft. We hit upon the following solution: simmer the potatoes until the chunks are almost tender (there should be just a tiny bit of hardness in the center when tested), then turn off the heat, cover the pot, and let gentle residual heat finish cooking the potatoes.

With the potato issue settled, we moved on to the leeks. We started out with two leeks. Although this a common amount in many recipes, we found that soups with so few leeks tasted anemic. We concluded that while potatoes may add the texture and heft to this soup, the leeks are the real source of flavor. We eventually decided on five or six medium leeks, including some of the green section, which makes for a more robust flavor. We tried slicing the leeks quite fine as well as leaving the pieces fairly large. Larger pieces are a substantial and appealing addition to this soup.

We like the simplicity of using just leeks and potatoes but wondered if other vegetables (especially onions and garlic) might add flavor. We found the presence of garlic, even in small amounts or when roasted, to be overpowering. However, onions added another level of flavor that complemented that of the leeks.