Despite the formal similarity and overlap in sense with pasterie, this is probably not the same word, cf. the commentaries to paster and pester1. See also pestrie, which may be the same word.
s.
1kneading (into a paste or dough):
(
1341
)
Item, une auge pur pester. Item, une table od deux trestels pur pesture. Item une peire de trestels travalles pur le braserie [...]
249
(
1373
)
nous avons assignez nostre bien amé servant Robert Cosyn nostre pesture, pur achater furment pur les despenses de nostre houstel, fuail et toutes autres choses necessaires pur l'office de nostre pesturie
i 122
pesturie (1280)