The crunchy sprouts of germinated mung beans have the green buds still attached. Choose sprouts that are crisp and dry; avoid wet or slimy-looking ones. Fresh mung bean sprouts are available at most grocery stores, but you can also easily grow your own. Soak 1 cup of mung bean seeds overnight in water, then drain and place them in a large bowl covered by a damp towel. Rinse the seeds twice a day for 4 to 5 days, or until the sprouts grow to 3 inches long. Fresh bean sprouts will keep for up to 2 weeks in a sealed container. Soybean sprouts are a good substitute. Find them at Asian grocery stores or health food stores.