Preheat the oven to 425 F. Toss together the tomatoes, red peppers, olive oil, salt, and pepper. Spread in one layer on a baking sheet and roast for 30 minutes. Remove from the oven and peel the skins from the peppers and tomatoes.
In a large stockpot over medium heat, sauté the garlic in 3 tablespoons of olive oil for 3 minutes.
Add the roasted tomatoes, roasted red peppers, basil, red pepper flakes, and vegetable stock. Bring to a boil and simmer for 30 minutes.
With an emersion blender, blend the soup to a creamy consistency. Check for seasoning.
Serve hot with a drizzle of extra-virgin olive oil on top and a slice of grilled Italian ciabatta bread on the side.