Serious Eats - seriouseats.com

There may be an astrological explanation...

Taurus sun signs, for example, are often notoriously picky eaters, and for them it is often about the texture, although sometimes other factors come into play. This may also be true for those born on the 6th, 15th or 24th of any month, as the "6" is the same vibration as Venus and Taurus.

Cancer sun signs sometimes have idiosyncracies, too, but more often they are a matter of comfort... or, actually, discomfort. Mustard, for example, usually contains vinegar, something that those of us with sensitive stomachs cannot always tolerate. This might also be true for those born on the 2nd, 11th, 20th of any month, as the "2" carries the same vibration as the Moon and Cancer.

One might also have other placements that could make one a picky eater, particularly in the 6th house, but to determine that, you'd need an actual horoscope.

(I have a Taurus daughter-- no mayo, tofu or mushrooms-- and a Taurus grandson, who is both picky and eccentric in his eating habits.)

Best of luck... try not to take it personally. It's probably not meant that way at all, but just someone who is in tune with what works for him food-wise and what does not. I sympathize, though, since it's hard to stifle one's creativity when cooking. Still, it is sometimes surprising how limitations can lead to even greater creativity.

Have you tried Mighty Peanut Butter yet? There's one with honey and one with maple.

I was inspired after eating the maple variety on various things, to try it on a ham sandwich. I know it sounds strange, but it was pretty good. Just be sure not to use too much.