What seasonal vegetable side dishes are appropriate for Hungarian Goulash?
[Possibly irrelevant-to-you aside: a true Hungarian goulash (as opposed to a North American or German or what-have-you goulash) is a soup. It includes a few root vegetables and possibly some "pinched noodles" (tiny little egg+flour dumplings) in the soup itself, but it is served with a hearty slice of bread or two, nothing more. So in that sense, the answer to your question is "mu".]

If what you're actually making is a meat stew with paprika (what in Hungarian would be called pörkölt), then the traditional accompaniments are either potatoes (with beef) or spaetzle (with any type of meat), and some sort of vinegary vegetable salad — either a cucumber salad, or some other vegetable dressed the same way as a cucumber salad (tomatoes, peppers), or pickled vegetables (sauerkraut-stuffed peppers, gherkins, that sort of thing). Another possibility is red cabbage, which (unlike cucumbers) is at least starting to be seasonal at the end of October.