1. In a 12-quart pot, render bacon on low heat for 10 minutes. Remove bacon, leaving the fat in the pan.
2. Bring pot to high heat and add shiitakes, then season with salt and pepper.
3. Remove mushrooms, lower heat and add the salsify, celery, onions, leeks and garlic and sweat for 20 minutes.
4. Drain liquor from the oysters. Add oyster liquor, chicken stock, bacon and shiitakes to the vegetables. Bring the liquid to a simmer, then add the cream. Season to taste with salt and pepper.
5. Right before serving, add oysters to the simmering liquid. Lower heat and poach oysters for 2–3 minutes, depending on their size. Stir in the scallions.
6. Ladle into bowls and garnish with parsley, truffle oil and cracked black pepper