In a large nonstick saucepan, heat the oil over medium heat. Add the onion, carrots and garlic. Cook for 3 to 5 minutes or until crisp tender, stirring occasionally. Stir in 1/2 cup of the broth. Cover and simmer for 10 minutes or until the vegetables are tender. In a blender container, place the drained roasted red peppers and the onion mixture. Cover and blend for 30 to 60 seconds or until smooth. Return the vegetables to the saucepan. In a small bowl, mix the flour with 1/2 cup of the remaining broth. Stir into the pepper mixture. Stir in the remaining broth, sugar, salt, black pepper and basil. Cook the soup over medium heat until the mixture boils, stirring occasionally. Boil for 1 minute. Remove from the heat. Stir in the sour cream before serving. Garnish each serving with cracked black pepper and a dollop of sour cream, if desired.