LENTIL SOUP

OUR IDEAL LENTIL SOUP IS THICK AND hearty, with lentils that are still intact. Many of the recipes we tested made delicious soups, but their texture was unappealing because the lentils had disintegrated into a thick mush.

We started our testing by focusing on the type of lentil. Red lentils fall apart when simmered and are best used in purees. We had better luck with the common brown lentils (sometimes tinged with green) that are sold in supermarkets. Although not perfect, our initial tests revealed that they make a better soup than red lentils. We had the best results with French green lentils, called lentils du Puy. They stay particularly firm when cooked, making them ideal for soups.

Since most supermarkets don't carry French green lentils, we decided to see if we could devise a method for handling common brown lentils that would make them less likely to fall apart when cooked. Our first area of research was salt.

Many sources recommend adding salt only after the lentils have been cooked, warning that they will toughen otherwise. We wondered if adding salt at the outset might make them less likely to disintegrate. We added salt at the outset, at the halfway point, and at the end of the cooking time and found no difference in texture. However, lentils cooked in liquid that was salted at the outset tasted better, having a more developed flavor.

Several sources suggested sautéing the lentils in oil before adding liquid to strengthen the outer skins. This technique works with rice—it is used to make pilaf and risotto—and it seemed worth a try. We found that lentils cooked for a while without liquid did in fact hold up better to the simmering process. When the soup was done, sautéed lentils were firmer than lentils added directly to the liquid without prior cooking. It seems that sautéing does indeed harden the lentil's outside layer of starch, producing a soup with tender lentils that do not fall apart.