Preheat oven to 425°. Place tomatoes, onion, carrots, and garlic on an unlined baking sheet (I leave the garlic in a small pile). It will fit pretty snuggly. Drizzle everything with olive oil, salt, and pepper.
3 lbs roma tomatoes*, 1 medium sweet or yellow onion, 3 tbsp garlic, minced, 3 large carrots, ¼ cup olive oil, ¾ tsp kosher salt, ¼ tsp black pepper, ground