Mix above ingredients together in non-reactive bowl.
Marinate for 1 hour prior to serving.
Whipped Celery Root
Put celery root in 1-quart pot, and cover with cream. Cook on medium heat until celery root is mush and water in cream has evaporated.
Transfer celery root mixture to blender. Add olive oil and blend until very smooth. Season to taste with salt.
Cool mixture in refrigerator. When mixture is cold, mix 1 pint heavy cream with ¼ cup celery root mixture in mixing bowl. Whip vigorously until stiff peaks are achieved. Season with salt.
To assemble, open your favorite oysters and place them on the half shell on a bed of ice. Place 1 tablespoon of apple mignonette on each oyster, and top with 1 teaspoon of whipped cream. Place celery leaf on top of whipped cream. Use inside stalks of celery to get lightest green leaves, these leaves are less bitter than outside leaves!