My homemade umeboshi are salt plums from apricots or mirabelles fermented the traditional Japanese way. As a result, they are by far more aromatic and flavorful than the packaged and preserved Umeboshi that you can buy outside Japan.
In elementary school, I was introduced to Xi Muoi 話梅, dried Chinese salted plums, by a friend whose mother was born in Malaysia. I was immediately in love with the new delicious taste! Since there weren't that many stores where you could buy Asian food in Hamburg in the early 80s, they were a rare delicacy. I wonder if the scarcity increased my love for them?
Umeboshi are also salty plums and similar in taste to Xi Muoi, but after drying they are pickled again and take on a great color with the addition of red shiso leaves. Their taste is equally fabulous. Umeboshi are truly one of the most delicious examples of successful wild fermentation of fruit.
Fermenting Umeboshi yourself
I have made it according to the traditional Japanese method. In the absence of real ume, I resort to small, yellow-red apricots from the market or take mirabelles, the small, yellow plums. Firmer fruits are better than ripe ones. Apricots, due to their thicker, velvety skin, become smoother and drier in the result, whereas mirabelles look beautifully varnished, remain juicier and become more acidic. That's why it's best to try out for yourself which fruit you prefer.
Instead of a wooden barrel, I used a small glass jar, and since I didn't have a board to cover the fruit on hand, I replaced it with baking paper.
- 450 gr. apricots or mirabelle plums
- 36 gr. salt ≙ 8%
- 100 red shiso leaves
- 1 fermentation vessel (clip-on glass without sealing ring)
- 1 piece of baking paper (a cut-to-size hardwood board would be better)
Put the small apricots or mirabelles in ice water for 4 hours and clean them very gently so that they do not get any bruises.
Then alternately layer them together with the salt in a fermentation vessel. The salt draws water from the fruit.
Place a piece of baking paper cut to size on top of the fruit, even better would be a hardwood board cut to size that fits inside the jar and closes off the fruit. Then weigh down with so many weights that the fruits are pressed down, squeezing the liquid out of them. This will create the brine necessary for fermentation, which should cover all the apricots (or mirabelles) after 3 days at the latest. Otherwise, please top up with 8% brine. If you need help calculating, feel free to visit my Salt Calculator.
Close the jar without sealing, or place a cloth with elastic over the jar to keep critters out.
After about 2-3 days, when enough brine has developed, take the brine and the fruits out of the vessel and back in, alternating with the fresh red shiso leaves. Then pour the brine over them. Weigh down again with baking paper and weights.
Wait 2-3 weeks. After this first fermentation phase you need sunny weather - or an oven.
Left apricots in the sun, right mirabelle plums in the oven
Spread the fruit on a makisu over a bowl and protect with a fly net. Either place outside in the sun, or dry in the oven with the door open and a maximum of 50°C convection drying. After about 3 days, the fruits should be dried. You can store the dried, finished umeboshi in a screw jar in the refrigerator.
Zero-waste product plum or apricot vinegar
After the end of the fermentation time, when you put the fruit into a screw-top jar for storage, please do not pour away the brine! It will by now have taken on a lovely pink color and a massively sour umami flavor. This liquid is called ume-su, a sweet and sour vinegar that is produced during ume production.
You can also fill the vinegar into a jar and store it in the refrigerator.
Mirabelle plums yield more umesu than apricots. On the other hand, apricot umesu tastes much better and lasts longer. Mirabelle umesu has tipped over after 6 weeks and tasted alcoholic.