OK. So I've put back a couple of things successfully, which is lovely as it opens up lots more things I can eat, and makes meals a whole lot less boring!
To do the challenge I ate something from the challenge food family for 6 meals in a row on the first 2 days of the test, then reverted back to the elimination diet for a further 2 days to give an responses time to come through, if there was nothing the foods went back in on a rotational basis - ie not every day! I then had a day of elimination + new food (if desired) before doing the next challenge. Elimination from then on includes the tested and OK food. Pretty standard stuff for this type of thing.
Nightshades (potatoes, tomatoes and peppers) where the first to be tested and they were fine. I know eggplant is also in this food family, but I really don't like eggplant so didn't bother with it.
I've just finished with the two days of eating corn in a variety of guises - On the cob, polenta, tinned, and so far have had no reactions to that either.
Its a time consuming process, and I'm pretty sure I've left the ones which will cause an issue (if any) to last, but we'll see.
Now you're updated.