The phrase "thin wafer" refers to a very thin and flat slice of a material, usually something like a cookie or a semiconductor. It means that the object is extremely thin, like a piece of paper, and has a flat, round shape. Full definition
So on goes fresh baby arugula, sharp slices of red onion, and thin wafers of radish, also a hefty drizzle of Mexican Crema, giving the sandwich a sour tang that makes this torta completely irresistible. (holajalapeno.com)
I've served this Christmas and New Year's Eve party recipe on one of my favorite cracker; the nearly paper - thin wafers from 34º Crisps. (thefitfork.com)
After this a man comes round with a nasty sort of dried - up fish, called «Bombay duck,» and a round thin wafer biscuit, which you are intended to pound up in your rice. (fieryfoodscentral.com)