Gather cilantro stems and remove any debris and dead or yellow leaves/stems.
DO NOT RINSE CILANTRO.
Trim any leaves off the bottom 2-3 inches of stems using sharp scissors.
Grasp the bunch firmly in one hand and trim the ends evenly off, to form a straight, clean edge.
Fill a glass jar with about 1 inch of clean, cold water.
Place the cilantro stems in the jar, so that the trimmed ends are flush with the bottom of the jar.
Cover loosely with a light weight, clear plastic bag. Don't secure it around the glass- allow for air circulation.
Every 2-3 days, remove the bag, and clean away dead or dying leaves. Trim ends again (about ⅙th of an inch).
Dump out old water, rinse jar clean, and add fresh water back to the jar, no more than 1 inch deep.
Place cilantro stems in the jar as before, with trimmed ends flush with the bottom of the glass.
Cover again loosely with the bag and place back in the fridge.
When ready to use some cilantro, remove only the portion of stems that you are using. Rinse with cold water and shake dry.
Repeat this process until the cilantro is used up, or eventually dies.