Preheat your oven to 350°F (180°C) to prepare for roasting the tomatoes.

Halve the Roma tomatoes and arrange them cut-side up on a baking sheet lined with parchment paper. Drizzle 2 tablespoons of extra-virgin olive oil over the tomatoes, then sprinkle with sea salt and freshly ground black pepper. Roast them for about 1 hour.

In a large pot, heat the remaining olive oil over medium heat and add the chopped yellow onion, diced carrots, and minced garlic along with ½ teaspoon of salt. Sauté for about 8 minutes until softened.

Add the roasted tomatoes to the pot, along with the vegetable broth, balsamic vinegar, and fresh thyme. Bring to a boil, then reduce heat and let simmer uncovered for about 20 minutes.

Let the soup cool, then blend until smooth, adding fresh basil leaves before the final blend. Return to pot.

Adjust seasoning with salt and pepper. Serve hot, garnished with fresh basil.