1. Sort and wash beans. Place in a large Dutch oven. Cover with water to 2 inches above beans. Cover and let stand for 8 hours or overnight. Drain.
2. Heat oil in a large Dutch oven over medium heat; swirl to coat. Add onion. Cover and cook 8 minutes or until tender, stirring occasionally. Add leek and chopped garlic; cook 2 minutes, stirring occasionally. Add soaked beans, stock, herbes de Provence, ham hocks, and bay leaf. Bring to a boil. Cover, reduce heat, and simmer 1 hour or until beans are just tender. Remove ham hock; cool slightly. Pick meat from bones; reserve meat. Discard bones and fat.
3. Add potatoes, turnip, and carrot to pan; cook 10 minutes or until tender. Stir in cabbage; simmer 4 minutes. Stir in parsley, thyme, vinegar, salt, and black pepper.
4. Rub toast slices with cut sides of garlic clove; spread evenly with butter. Serve toast with soup.