Just avoid all processed foods if you can. You can't trust them.
Anything with lemon or lime juice, like tortillas and jam, may contain significant amounts of sulfite, and they're not labeled as such. Lemon and lime juice in bottles is heavily sulfited. It's only clean if it's frozen or if you squeeze it fresh from the fruit itself. Sulfite only has to be labeled if the processor adds it directly, not if they bought the juice in bottles.
Avoid anything made from corn. Corn starch especially, is sulfited in the processing. Corn itself should be clean.
I have not heard of grains being sulfited, but nuts often are. I recently ran into a bad reaction from Costco cashews. I had eaten them for years, but they got some new ones that were lighter in color and I got a scary tachycardia. I reported it to the company, but I don't think they did anything. They just buy the stuff, don't do the processing.