Place the grapes in a food processor. Process with 3 or 4 on and off turns, until coarsely chopped. Set aside.
In a large skillet, melt butter; add onion and cook until just tender, about 5 minutes. Add rosemary and oregano. Cook for 1 minute. Add chopped grapes and vinegar; cook 1-2 minutes more until heated through. Transfer to a serving bowl. Serve using a slotted spoon. Enjoy!