In a large pot, heat the oil. Add the garlic, celery, carrots and onion and cook over moderate heat, stirring occasionally, until softened, 7 minutes.
Add the tomatoes, bay leaf, lentils, smoked turkey and 6 cups of water. Add instant chicken bullion for extra flavor and bring to a boil. Cover partially and simmer, stirring occasionally, until the lentils are very tender, 1 hour.
Add the potatoes and simmer until tender, 10 minutes.
Remove the turkey meat from the bones and return it to the soup; discard the skin, bones and bay leaf. Add the parsley and season the soup with salt and pepper. Ladle the soup into bowls and serve, passing the cheese at the table.