Choosing, Picking and Rinsing

• Brown lentils, most commonly sold in 1-pound bags, can be found in the beans and rice aisle of your grocery store. Look for the harder-to-find varieties such as French green and red lentils in the ethnic section, or visit specialty stores that sell Middle Eastern food. Like all non-processed legumes, lentils require that you rinse and pick them over before you cook them. To avoid stones in your soup, pour the lentils into a strainer or colander and rinse under cool water. Swish the lentils with your hands and look for debris such as small rocks, leaves or bits of sticks; also remove any discolored or partial lentils.

Cooking to Store

• To pre-cook your lentils, cover with 1 inch of boiling water on medium-high heat. Once they come to a boil, turn the heat down to low and simmer, uncovered, for about 20 to 30 minutes. Check the water level and add more if necessary; lentils double in volume as they soak up the cooking water. Small red or orange lentils cook more quickly than plain brown or green lentils, making them a good choice for creamy or pureed soup recipes. Green lentils take the longest to cook and hold their shape well, giving more texture to soup. Plain brown lentils become tender in about 25 minutes. Allow the lentils to cool in their broth for no longer than an hour before storing.

Packing Them Up

• To keep the shape of your lentils intact during storage, add a splash of white vinegar or lemon juice to your cooked lentils and give them a quick stir. For smooth and creamy soups, transfer cooled and cooked lentils to a blender or food processor, or use an immersion blender to puree your lentils. Store the desired serving-size amount of cooked lentils with their liquid in plastic containers with a tight-fitting lid. Lentils stored this manner keep for up to five days in the refrigerator and five to six months in the freezer.

Taking Them Out

• To use frozen lentils in your soup recipe, you have two choices: Either thaw the lentils the night before in the refrigerator or use the frozen cube of lentils. With both methods -- and when you use them straight from the refrigerator -- add your cooked lentils to your soup after you have sauteed the bacon, onions and other vegetables. Adjust the amount of broth to accommodate the broth packaged with your stored lentils. Any tomatoes or acidic ingredients added to your soup will not affect your cooked lentils, making it east to throw together a fast dinner.