Long-storing legumes, including beans and lentils, hold an important place in the world's cuisines as high-protein foods that aren't quickly perishable. Aside from their well-known role as a pantry staple, lentils or other legumes can also be sprouted in a matter of days as a healthful, year-round green vegetable. You can sprout the familiar olive-green variety, tiny red lentils or exotics such as Puy and beluga lentils with equal ease.
You'll need very little equipment to start sprouting your own lentils. A large jar is the usual choice of venue for the legumes, ideally a 1-quart or 2-quart Mason jar. Other jars work equally well, but the two-part lid of canning jars is especially convenient. The jar must be covered with mesh or cheesecloth during the sprouting process, to provide airflow and prevent spoilage, and the mesh is easily secured in place with the canning jar's ring. Some health food stores stock special mesh lids to fit canning jars. If you use a different type of jar, secure the mesh to the jar's threads with elastic bands or tightly tied twine. Sanitize the jar with diluted bleach before you start.
Start by pouring your lentils out onto a plate or other flat surface, and picking them over. Remove any that are wormy, wizened or damaged, and pick out any stones or stems that might have gotten into the packaging. Transfer the lentils to the jar, and cover them with plenty of fresh, cold water. Skim off any debris that floats to the surface. Let the lentils stand for 24 hours, then drain and rinse them thoroughly. Cover the mouth of the jar with mesh or cheesecloth, then screw the ring on to hold it in place. Place the jar on its side, so the lentils make a relatively shallow horizontal layer -- they'll triple in size as they sprout, so don't do too many at once -- and leave the jar in a place where it will receive plenty of indirect light.
You'll start to see tiny "tails" growing from your lentils in as little as 12 to 24 hours. They'll usually be ready to harvest after two days, or up to five days, depending how large a sprout you prefer. During that time, like any other infants, the nascent sprouts will require a bit of your care and attention. At least twice each day, rinse out the jar of lentils with fresh, cold water to reduce the risk of spoilage or bacterial buildup. With the mesh or cheesecloth in place, that's as simply as running water in through the mesh and draining it back out again. Rolling the jar once or twice a day, so the lentils have even exposure to light and moisture, also helps.
After 36 to 48 hours, the sprouts on your lentils should be 1/4 to 1/2 inch long, and show the first signs of leaf formation. They're fully edible at this stage, lending a juicy crunch to grain-based salads or stir-fries. If you let them grow for another day or two the sprouts will be longer and thinner, with green leaves beginning to form at the ends. At this stage they're less "bean-y" and more of a green vegetable, like alfalfa sprouts. Add a pinch -- or a handful -- to your favorite green salad, or mound them onto sandwiches for their crunch and moisture. The sprouts also make a fine garnish for brothy, Asian-style soups such as pho.
Once your sprouts are mature, place a regular lid on the jar and transfer it to your refrigerator for storage. Eat the sprouts within five to seven days, to minimize the risk of spoilage or foodborne illness. Because they're often eaten raw or lightly cooked, sprouts can be problematic and should be avoided by the elderly, pregnant women or anyone with a depressed immune system. If you'd like to reduce the risk, you can treat the lentils before they're sprouted. Heat a bottle or two of 3 percent hydrogen peroxide -- the kind you get at any drugstore -- to 140 degrees Fahrenheit. Stir the lentils into the peroxide, and hold them at that temperature for one minute. Then drain them, rinse them well, and start soaking the disinfected lentils.