Umeboshi is a traditional Japanese pickle made from plums. The ingredients for making umeboshi include plums, salt, and red shiso leaves. To make umeboshi, start by washing the plums and removing any stems. Then, place the plums in a large bowl and sprinkle them with salt. Let the plums sit for a few hours to draw out the excess moisture. After that, rinse the plums to remove the salt and transfer them to a clean jar. Add red shiso leaves to the jar for added flavor and color. Finally, cover the jar and let it sit at room temperature for a few days to ferment. Umeboshi can be enjoyed as a condiment or used in various dishes like rice balls or onigiri.