The vinegar in this can be replaced with cider vinegar or another mildly-flavoured vinegar (and possibly by a dash of balsamic vinegar, though with precautions).
If you're not a fan of raw onions (I know the H finds them too aggressive), you can heat up the onion rings for a bit on a hot stove (either by frying them for a bit, or by dumping them into hot water for 30 seconds. I prefer to fry them, as I find blanching them leaves them a bit soggy).