[Pe-Sozu]

Well, the topic describes itself perfectly.
I found the recipe in my inventory right after that shameful cut scene of my ass handed to the king slayer at act 1.

As far as I know, this game doesn't support any sort of item reload from the last playthrough, so I don't know what happened here but I'm glad it did and I wonder what's gonna happen next. Am I gonna be able to find it in my next playthrough? (Of course, in act 1)

any ideas about why it happened and how I do it again?

[Guy N'wah]

There's an occasional piece of weird random loot (all the cases I have heard of are a schematic for a random weapon, often one that doesn't belong in Act I or isn't even otherwise in the game) that shows up in Act I. So far as I know, it is both very rare and very random: you cannot predict where you will find one, whether you will find one, what it will be, or whether there will be one in the same place as in the last game.