Yes I have investigated tiger nuts. They are a different animal to maize. I drive to Valencia where a lot of it is grown and buy sacks of the biggest and freshest "nuts" I can find. Here is a suggestion, Instead of soaking them in water, soak them in Tiparros fish sauce, available in bulk from chinese supermarkets. I found it vey succesful and yes tiger nuts do swell up a lot compared to maize.