For roasted grapes:  Heat oven to 425 F. In bowl, toss grapes with vinegar and oil. Place on baking tray and roast for 10-15 minutes. Set aside.

For spicy yogurt:  Mix yogurt and hot sauce together.

To serve:  Spread each flatbread with spicy yogurt and top with chicken, feta, lettuce, onions, and roasted grapes.