For a brief window in the early summer, Japanese and Korean markets sell these tiny green fruits. Prunus mume, or in Japanese, 梅:うめ, is actually an apricot, but always referred to as a plum. Originating in China, ume are now widespread throughout East Asia and are the main ingredient in the salty pickled plums called umeboshi and in plum wine.In San Francisco, fresh ume are in these stores Right Now: Woo-Ri Korean Market, Nijiya, and Uoki Sakai markets in Japantown. They're also available at the Berkeley Bowl. For those of you that don't have nearby access to a Japanese grocery store, Mitsuwa will take orders by phone and mail some to you. Call Mitsuwa at 1-877-MITSUWA (877-648-7892).
The plums are small, smaller than a golfball, and green to yellowish-green in color. Sometimes they have a peach-colored flush on them.
Ume plums are very astringent and can't be eaten raw - they'll give you a tummy ache. But in salted or alcohol-preserved form, they're perfectly safe to eat and are quite delicious. They can also be made into a jam. In China, Japan, and Korea, the sour juice of the plum is extracted and made into a refreshing summer beverage. Ume plums are considered to be good for your health.