ceviche

Here is an interesting etymological speculation (link for ceviche < escabeche < Arabic al-sikbāj 'sweet and sour stewed beef' < Persian sik 'vinegar' + bā 'broth'. Other etymolgies have been proposed and are mentioned in the Wikipedia article that Faldo linked to.

As for the process, I thought it was simply called marination.

Ceci n'est pas un seing.