For the last several years, I have had a research issue. Provoked by some of the discussion in this post on /r/AskHistorians (I am gothwalk in those comments), I went looking for evidence of vinegar pickling in Medieval Europe. I did not find it. There is brining and fermentation in plenty, but I was completely, completely, unable to find evidence of vinegar pickling before 1600. I have spent cumulative weeks on this.

There're even two books about the history of pickles; Pickled, Potted and Canned by Sue Shepherd and Pickles: A Global History by Jan Davison, both of which sort of shuffle gently around the issue (or possibly they just didn't think it was an issue, not being quite as obsessed with reonstructive cuisines as I am).

However, I have finally found evidence, and it's even written. It turns out there are multiple mentions of it (including making it clear it's vinegar, not just something else translated as pickling) in the Tacuinum Sanitatis, a medical treatise translated from an Arabic original (Taqwīm aṣ‑Ṣiḥḥa, by Abū 'l-Ḥasan al-Muḫtār Yuwānnīs ibn al-Ḥasan ibn ʿAbdūn ibn Saʿdūn ibn Buṭlān) to Latin (by several different translators, mostly in Italy) in the mid-13th century. There's a modern-ish English edition published in 1985 (with reproductions of period illustrations) called The Four Seasons of the House of Cerruti, by Judith Spencer. I discovered this in a reference in Julia Skinner's Our Fermented Lives, which is also an excellent book.

A man harvesting pomegranates

miniature from a copy of Ibn Buṭlān’s Tacuinum Sanitatis (11th century)

Tacuina sanitatis (XIV century)