(1) For recipe writers, onions come in only three sizes, ‘small’, ‘medium’, and ‘large’, whereas onions in your shopping bag vary from the size of a shallot to that of a curling stone. So an instruction such as ‘Take two medium onions’ sets off a lot of pedantic scrabbling in the onion basket for bulbs that fit the description (obviously, since medium is a comparative term, you have to compare across the whole spectrum of onions you possess). (2)
