Heat olive oil in a large, heavy-bottomed pot on medium heat and add the onion, shallot, salt, and peppercorns. Cook until slightly translucent, about 5 minutes. Add the carrots and potatoes and cook until slightly tender. Add broth, tied herbs, and bring to a boil. After reducing the heat to a simmer and cook covered for about 45 minutes. Until the vegetables are very tender. Remove the herb bundle and allow the soup to cool slightly.