It may sound silly, but I've made these roasted grapes on many occasions and they always make a lasting impression. This appetizer gets requested and referred to more than any other I make and I want to encourage you to give this simple and delicious appetizer a try.
Preheat your oven to 425-450 degrees (you decide how your oven responds). Place non-stick foil on a cookie sheet.
Wash and lightly dry your fresh, seedless grapes. Leave just a small artistic cluster still on the vine, and pluck the rest of them from the stem and scatter on the foil. You'll want the ones on the vine for artistic effect, but know that if you roast them on the vine, most of the flesh clings when you pull it off to eat. That's why we're plucking most from the vine before roasting.
Drizzle with a little olive oil and a splash of balsamic vinegar. I always use a specialty vinegar by Beekman 1802: Fig & Elderberry Blaak Drizzle.
Keeping an eye on them, roast the grapes for 10-20-30 minutes until they split, sizzle, char and collapse. Sometimes it works faster than others, probably based on the sugar content.
Once they have cooled a bit, arrange them on a platter (with toothpicks nearby) with your favorite cheese and cracker bites. We're heading into party season - Enjoy!