Curiously, I can't eat yams. When I do, I often end up with some kind of nasty burn on my tongue. I have the same response to citrus fruits (my favourites), a

Curiously, I can't eat yams. When I do, I often end up with some kind of nasty burn on my tongue. I have the same response to citrus fruits (my favourites), and sweet-and-sour sauces.