Wash a wide mouth quart-sized mason jar and rinse it well to remove any soap residue.
Prepare a piece of window screen to fit your wide mouth mason jar. I use polyester window screen on my sprouting jars, drawing a circle on the screen using the mouth of the jar as my pattern. I cut around the circle. Then my sprouting screen is ready to use. If you don’t have spare window screen laying around your kitchen, you can order specially made sprouting screens online.
Place bean seeds in a one-quart mason jar.
Place the screened lid on the mason jar.
Fill the jar ½ full with cold water. Let the mung beans soak overnight.
Rinse the mung beans in the morning and turn the jar upside down to drain.
Rinse and drain your bean seeds twice a day for 4 to 6 days. The mung beans are ready to eat when the white sprout is at least 1.5 cm long, but they can be grown out until they're 3" long.
Notes
If the sprouts are exposed to light while they are growing the leaf tip will turn green on days 5 and 6. If the sprouts are kept in the dark, they will remain white, like the bean sprouts from China. I like my bean sprouts to be a bit green.
No sprouting lid? You can simply cover the top of the jar with several layers of cheesecloth fastened in place with a rubber band.
Store sprouts in the fridge for up to a week. Rinse them once a day to prevent them from drying out.