The products we used:
Pickled… plums?
Plums grow in abundance in Japan, so when it’s time to harvest, they need a plan for preserving the fruit they can’t eat immediately. In the west, it’s not uncommon to dry or even candy fruit. Japan has different plans for their plums, however. They prefer to make fruity liqueur, unique plum jam, and even pickle those plums. Pickled plums are called umeboshi in Japanese.
The Western mind might find the idea of pickling fruit somewhat disturbing. Americans like me like sweet or sour fruit, not salty and sour fruit. Alcohol infused plum jam probably sounds alluring. After all, rum raisin ice cream is amazing. Tangy-salty plum pickles? Probably not as alluring.
However if you are a fan of pickled foods generally–and if you are, you should check out our guide for making nukazuke–then I urge you to keep an open mind about pickling your plums.
Foods with Umeboshi
As is common with pickled food, umeboshi is commonly used sparingly to add acid and enhance other flavors. Pickled plums are most commonly added to onigiri or bento boxes, but are sometimes added to rice porridge or even somen. If you are one of our many customers on their way to rice nirvana and you consume a lot of rice or rice-based Japanese food, then umeboshi might be a good way to bring variety to your go-to favorites.
Timeline
If all this talk has you intrigued, then you’re probably interested to know how much time and work goes into pickling plums. First, here is the timeline you should expect for this process from start to finish:
- Salt-Pickling Plums: Mid to late June
- Adding Red Shiso: Late June to early July
- Sun-Drying for 3 Days: Mid to late July, during clear weather
- Completion: Ready to eat.
In total, it takes approximately one to one and a half months to complete the process, and that when this blog is published, it’s time to start the process. Now lets look at the process.
Ingredients
Salt-Pickling
- Ripe plums: 1.5 kg (3.3 lbs)
- Coarse sea salt: 300 g (10 oz, 18% of plum weight)
- Shochu (35% alcohol): 75 ml (1/3 cup)
Red Shiso Preparation
- Red shiso leaves: 400 g (14oz, 20% of plum weight)
- Coarse sea salt: 40 g (1.5 oz, 20% of shiso weight)
- White umezu (plum vinegar created during the salt-pickling process): Enough to cover shiso
Equipment Needed
- Pickling container (with inner and outer lids, acid-resistant material)
- Weight (for holding the lid down): 3.5 kg (11 lbs)
- Large, flat bamboo tray or colander
1. Choosing the Perfect Plums
Select ripe, yellow plums, soft and fragrant, for the best flavor. Avoid green, firm plums, which require extra soaking, or overripe ones that turn mushy. Find them at farmers’ markets or Asian grocers in mid-June. Check for blemishes—nobody wants a moldy umeboshi ruining their bento. Pre-order at your local store to snag the ripest batch.
2. Washing and Prepping
Gently wash the plums under running water to remove dirt. Discard any with bruises or cuts to prevent mold. Pat dry with a clean cloth, then use a bamboo skewer to carefully remove stems without piercing the flesh. This is the most labor intensive part of the process, so once you’re finished here, take a breath and then keep going.
At this point, you can also spray or toss the plums with shochu to sterilize. Otherwise, you can do what we did and add the shochu while following the next step.
3. Layering Plums and Salt
If you use special pickling bags from RISU, then you can put one in a pickling container box (also by RISU). Otherwise, you can sterilize the container itself with some boiling water or alcohol. After sterilizing, sprinkle a handful of salt, add a layer of plums, and repeat, ending with salt.
4. Place Lid and Weight
Place the inner lid on top, add a weight (equal to the plum weight), and seal with the outer lid. Wrap in newspaper, label the date, and store in a cool, dark place.
Container and Weight Selection Guide
Use this table to help you decide what container and weight sizes you need.
| Plum Quantity | Container Size | Weight Needed |
|---|---|---|
| 1–2 kg (2.2–4.4 lbs) | 2–3 L (0.5–0.8 gal) | 2–4 kg (4.4–8.8 lbs) |
| 3–5 kg (6.6–11 lbs) | 5–7 L (1.3–1.8 gal) | 5–10 kg (11–22 lbs) |
| 6–10 kg (13.2–22 lbs) | 10–15 L (2.6–4 gal) | 12–20 kg (26.4–44 lbs) |
Note: The weight should match the plum weight initially, reducing later.
5. Waiting for White Umezu
After about a week, white umezu (plum vinegar) will rise. Leave just enough to cover the plums and transfer the excess to a clean container for later. If the umezu doesn’t cover the plums, add more weight. Check daily to ensure the plums stay submerged.
6. Adding Red Shiso
Red shiso is an herb that adds a red color to the pickled plums. Finding red shiso can be rather difficult, so you can consider this step optional if you don’t have access to it. Umeboshi that is prepared without red shiso is called shiroboshi ume–white pickled plums.
In late June, prep red shiso leaves. Wash thoroughly, drain, and knead with salt in a bowl. Squeeze out the dark liquid and discard. Repeat with more salt. Add reserved white umezu to the shiso until covered, kneading until it turns vibrant red. Spread the shiso over the plums, pour in the shiso-infused umezu, and replace the weight. After 2 weeks, when the liquid rises 2 cm above the inner lid, switch to a lighter weight until the rainy season ends.
7. Sun-Drying (Doyoboshi)
In mid to late July, during clear weather, dry the plums for 3 days. On day 1, remove shiso, drain, and spread leaves individually on a bamboo tray. Arrange plums with space between them and place the container with its liquid in the sun. Flip plums halfway and adjust tray positions. Return everything to the container at night. On days 2–3, repeat but leave the plums and shiso outside overnight for dew exposure. The plums are ready when the skin is soft and wrinkles are pinchable. If it rains, bring indoors.
Tips for Success and Avoiding Pitfalls
Sterilize all equipment with boiling water or shochu to prevent mold. Use only coarse sea salt—table salt won’t do. If mold appears, remove affected plums or shiso, boil the umezu, and dry the plums before returning them to a clean container. For shiso, buy early and store salted in the fridge if needed. If your umeboshi are too salty, soak briefly before eating.
When Are They Ready?
Store the plums in a clean jar with dried shiso and some umezu in a cool, dark place. They’re edible immediately but improve after 6 months, hitting peak flavor at 3 years. Grind dried shiso into yukari powder, and use umezu for dressings or pickling. Refrigerate if you’re concerned about storage.
