In a heavy 2-quart saucepan over medium heat, bring the heavy cream and oyster liquor from the oysters to a simmer. Remove from the heat.
Melt the butter in a large sauté pan over medium heat. Add the celery and a pinch of the salt and sweat for 3 to 4 minutes. Add the onion and continue cooking until translucent, 4 to 5 minutes. Add celery seed, hot sauce, and oysters, and cook until the edges of the oysters start to curl, 1 to 2 minutes.
Transfer the oysters to the carafe of a blender and add enough of the cream just to cover. Puree until the mixture is smooth. Return the remaining cream to medium heat, add the pureed mixture and cook until heated through.
Just before serving, add the lemon juice, chopped herbs, and season with salt and pepper, to taste.