Preheat the oven to 350°F and line a large baking sheet with parchment paper. Place the tomatoes on the baking sheet, drizzle lightly with olive oil, and sprinkle with salt and pepper. Roast for 45 minutes, or until the edges just start to brown and the insides are still juicy.
Heat 1 Tbps. olive oil in a large sauce pan over medium heat. Add the onions, carrots, garlic, garlic powder, and salt and cook until soft, about 8 minutes. Stir in the tomatoes, vegetable broth, vinegar, thyme leaves, and oregano or zataar leaves and simmer for 20 minutes.
Let the soup cool. Place it in a blender (like a Ninja or Vitamix), add basil, and blend for about a minute and a half until creamy. Taste for seasoning and adjust accordingly.
Garnish the soup with a drizzle of olive oil, basil, and croutons. Enjoy!
