Sugar-Salt-Vinegar Pickled Plums
C: Pickled plums~!
Translator Notes
About the Recipe name - Sashisu Umeboshi
Regarding the name of the recipe, it is さしす梅干し (sashisu umeboshi). If you look up sashisu on Jisho, you get さしすせそ (sa-shi-su-se-so), all the Japanese syllables using the consonant S.
さしすせそ refers to the 5 fundamental seasoning used in Japanese cooking, in order: sugar (satou 砂糖), salt (shio 塩), vinegar (su 酢), soy sauce (shouyu 醤油, perhaps the ateji seiyu 正油) (view comments here), and miso (味噌). So, sashisu would refer just to the first 3 seasonings, hence sugar-salt-vinegar.
Definition of ateji (当て字/宛字): “kanji used as a phonetic symbol, instead of for the meaning” (Jisho).