Marinated Mushroom, Tomato, and Scallion Skewers

Whisk garlic, oil, vinegar, thyme, red pepper flakes, 1 tsp. salt, and 1/2 tsp. black pepper in a medium bowl. Transfer mixture to a resealable container or plastic bag and add scallions, tomatoes, and mushrooms. Marinate until ready to cook, at least 15 minutes. If using wooden skewers or branches, soak them in water at least 10 minutes. Skewer scallions, tomatoes, and mushrooms, dividing evenly and leaving about 4 inches of empty skewer at the bottom. Reserve leftover marinade. Prepare a campfire for medium heat. When it's ablaze, carefully place skewers vertically in the ground around the fire; they should be close enough to the flames that the ingredients begin sizzling within a few seconds. Cook, rotating skewers occasionally, until scallions, tomatoes, and mushrooms are caramelized or charred in spots and mushrooms are tender, 10 –15 minutes. Transfer skewers to plates, season with salt and black pepper, drizzle with reserved marinade, and serve.