Place a 5 QT Saucier over medium heat. Add butter to the hot pan and swirl to melt completely. Sprinkle the flour over the butter and whisk until smooth. Cook the roux, whisking occasionally, until the color changes to golden brown and it smells toasted, 8–10 minutes.

Carefully whisk in white wine until smooth. Add chicken stock while whisking continuously. Bring gravy to a simmer and reduce the heat to maintain a gentle simmer. Using butcher's twine, tie together the thyme and sage and add the bouquet to the gravy. Season with salt.

Simmer gravy, whisking occasionally, until it’s smooth and silky and the raw flour flavor has been cooked off, about 20 minutes. Stir in the lemon juice. Strain the gravy to remove the herbs and any lumps that may have been missed. Serve immediately or cool and store.