First, I boiled the teeny potatoes (both red and yukon gold) to give them a head start. Meanwhile, I sliced yellow squash, zucchini, and some fresh onion. I sprinkled on a little salt. Sometimes I'll marinate vegetables destined for the grill in some balsamic vinegar, but when I saw that my bottle of rice wine vinegar was just about empty, so I used that instead. Just a couple tablespoons.
Then I drizzled on the olive oil, mixed it around, and let it sit until I was ready for it.
I fired up the grill, put the grill frying pan on the grill to let it get hot, then dropped in the vegetables and potatoes. I stirred them around every once in a while to let them cook and brown a bit.
Little effort, lots of flavor.
And no, you don't really taste the vinegar. It's not like a pickled vegetable, it's just a flavor enhancer. You can leave it out, or use any other vinegar you like. As I said, balsamic is usually what I use, but sherry vinegar is nice, or a wine vinegar or even cider vinegar. Or lemon juice. It adds a little brightness, not tartness.