Shauna, have you ever considered that you might have chemical sensitivities?
It is something we looked at, but doesn't seem to be the case. Organic produce, with less chemicals, actually tends to cause more gluten issues than conventional produce, at least with the bigger farms. Lots of organic farms seem to use sprays and such that have less processed grains and grain derivatives in them, I'm assuming as a binder.
Has someone found a good cleaning solution or method?
There were a couple things we used to do that we eventually had to abandon when we grew more sensitive. But they did help.
One thing for beans and whole grains is to sort and wash. Pour them out on a dark surface, like a black cookie pan, and take out any suspicious looking grains that don't look the same as the grain/legume you are sorting. Then wash them with soap and water in a mesh sieve (metal coffee filter, for teff).
Fill up a bowl with soapy water, put the beans/grains in the sieve and put it in the water, then scrub it around in against the inside of the sieve for about 20-30 seconds. Dump out the soapy water, rinse out the bowl, and repeat the soap washing 1-2 more times. Then rinse that way 2-3 times to get all the soap off.
With beans I have reacted to, I have washed the same batch that was originally tested and then re-tested it later. The reaction was less after washing in this manner. So I do think that it may be of some use in lowering any potential low level gluten, especially in items that it might be difficult to clean. Usually, if I am not using it right away, I needed to dry these out before storing, either in the open air or the oven on warm.
It's only useful for items that are sturdy enough to scrub against the sieve, though.
For softer, smooth skinned produce, washing with soap and water, then peeling, then washing with soap and water again, helped a bit.
For some, I wasn't ever able to find a solution that made any difference, like the strawberries you mentioned, Kareng. Broccoli, peaches, and cauliflower have been in that category, as well. Probably someone more skilled with a knife might be able to peel the peach, but I always ended up with a big, mushy mess instead, LOL.