Tear two 12x20-inch pieces aluminum foil; overlap pieces slightly. Place carrots, potatoes, garlic, cumin, and thyme in center of foil. Drizzle with oil and season with salt and pepper. Fold edges of foil up and over to create a packet; pinch edges to seal. Grill, turning packet occasionally, until potatoes and carrots are tender, 28 to 30 minutes. Open packet and drizzle with vinegar.