Umeboshi (梅干し) are small, salted/pickled plums (more like apricots) that are popular in Japanese food. We get boxes of umeboshi from my in-laws in Japan regularly, and these are really nice, organic ones. My wife and I love to eat them over rice, or with Japanese curry.
Umeboshi look funny to Westerners, and they’re extremely sour, but once you get used to them, they’re quite good. Fortunately, you can often find sweeter varieties of umeboshi which are mixed with honey. But even the sour ones are very good if you mix them with something else. For example, my wife and I like to boil some chicken, chop it into thing slices, and mix it with chopped cucumber and chopped umeboshi (seeds removed of course). The combination of the three is very refreshing.
But also for vegans and vegetarians, umeboshi is an excellent food because it’s very nutritious, tastes good and has no animal products. A popular food in Japan is onigiri (also called omusubi), which is a kind of rice ball with umeboshi in the middle, wrapped in toasted seaweed. They’re popular for picnics and such.
Finally though, umeboshi has many health benefits. First, it helps digestion a lot. I notice that if I eat umeboshi regularly (maybe 1 a day), my heartburn goes away for a while. Plus, like many pickled foods, it has a lot of vitamins and minerals, and if you get the good quality umeboshi, no artificial flavors either.
Umeboshi is an acquired taste, but pickled fruits are a very common food all over Asia (Vietnamese xí muội for example), and the world, and have a lot of benefits for the body, but also work very well in cooking too.
P.S. Please don’t be like these girls.