How to Make It
Fill a medium bowl with cold water and add the lemon juice. Peel the salsify and cut into 1/4-inch dice. Add the salsify to the lemon water.
In a large saucepan, cook the bacon over moderate heat until crisp, about 5 minutes. With a slotted spoon, transfer the bacon to paper towels to drain; reserve 2 tablespoons of the bacon fat in the saucepan.
Add the onion to the saucepan and cook over moderate heat until softened, about 5 minutes. Drain the salsify. Add it to the saucepan and season with salt and black pepper. Cover and cook over moderately low heat, stirring occasionally, until the salsify is almost tender, about 10 minutes. Add the wine to the saucepan and bring to a boil. Add the clam juice, water and thyme. Cover and simmer over moderately low heat until the salsify is tender, about 10 minutes longer.
Add the cream, oysters, oyster liquor and cayenne and simmer for 5 minutes, or until the oysters are just cooked through. Discard the thyme sprigs. Season the chowder with salt and black pepper and ladle into warmed bowls. Top with the bacon and parsley and serve.