Heat the oil in a large pot over medium heat. When hot, add diced onions and carrots with 1/2 teaspoon each of salt and pepper.
When onions have softened and are translucent, add in roasted garlic and tomato paste. Cook while stirring for 30 seconds.
Add in tomatoes and stock and stir well.
Bring to a boil, then reduce heat to low, cover, and simmer for 2 to 3 hours.*
Add in dried basil, then puree in a high powered blender, in batches to prevent overflow and burning while handling hot soup.
Serve hot and store leftovers in the fridge for up to 5 days, or in the freezer for up to 3 months.
*You can use 10 to 12 peeled and seeded tomatoes instead of canned tomatoes if making in the fall.(About 2 lbs)*The soup can be pureed after 30 minutes, or whenever the carrots are very tender, but for best flavor allow to simmer for a few hours.