An Etymological Dictionary of the German Language/Brei
Brei, m., ‘broth, pottage,’ from the equiv. MidHG. brî, brîe, m., OHG. brîo, m., allied to Du. brij, AS. brîw, ‘pottage’; Goth. *breiwa- (Goth. *breiws is related to OHG. brîo in the same way as Goth. saiws to OHG. sêo). It is hardly possible that the word is connected with the root brū̆, discussed under brauen. Did a root brī̆, ‘to cook,’ exist? comp. OIc. brîme, ‘fire.’ Gr. ορίσσω (root φρῖκ) has been suggested.