In a large, heavy skillet, heat olive oil over medium heat. Add the shallots, garlic, carrots and zucchini, and sauté for 2 to 3 minutes, stirring frequently. Season with the salt and pepper and transfer to a slow cooker. Stir in the diced tomatoes with any juices.
In a medium bowl, whisk together the tomato paste, herbes de Provence, and broth just until blended. Pour over vegetables in the slow cooker, cover, and cook on low heat for 4 hours.
Transfer soup to a heatproof dish and allow it to cool for 10 minutes. Pour into a blender or food processor and blend the soup (in batches, if necessary) until smooth. Soup can be reheated in microwave if it becomes too cool.