For best taste use freshly picked mint, and preferably organic
Rinse mint with cold water and let dry
Pick the green leaves and discard the stems
Lay green leaves on a towel by a window (but NOT in direct sunlight) and in a well ventilated area and let dry for 5-10 days. Note that direct sunlight will blacken the mint leaves and weaken their taste. Alternatively you can dehydrate them in a dehydrator.
Discard any yellowed leaves
Place dried mint leaves in food processor, and let it run for a few minutes until it turns into a powder
Filter the resulting powder mint in a fine filter/strainer to remove any stem leftovers
Store filtered dried mint in an air-tight container/jar in a cool/dry place away from sunlight
Notes
You may also like to leave the dried mint leaves as is, without grinding, and preserve them in an air-tight jar to use with teas. You may also bundle the green mint bunches and tie them with a rope to the ceiling on a balcony/porch in a place that doesn’t get direct sunlight. In this method, they tend to dry faster.Dried mint can last several months if kept in an air-tight container.