What is the make of your cutting board. When you say "red oak, walnut and ash," I hope you did not make your board out of these combinations. Red oak inpart a taste to your food; it also is very porous (you can blow bubbles with it) therefore may trap food particles or juices inside the cutting board--spell that stale. Walnut may have a taste,too -- I'm not sure. Ash -- I have no idea. Most cutting board are made of maple because it is hard enough, have no bad taste, and contain no harmful chemical in the wood (pale means no tanic acid which may be good in your tea but not your food -- watch out walnut)
Theses are just my guess and definitely did not pass and scientific scruntiny. May be someone on this BBS can correct me.

ps. what kind of glue you used?

: I know this isnt about kayaking but there seem to be some pretty
: knowledgeable people concerning wood here, so, what is the best finish for
: a cutting board of red oak, walnut and ash? Thanks for playing along.
: Elliott