Casamento'S Oyster Soup - cooking recipe

Ingredients

3 1/2 cups water
2 dozen oysters, freshly shucked, drained
1/2 cup celery, chopped
1/2 cup green onion, chopped
1/2 cup onion, chopped
1/4 cup unsalted butter
1/2 teaspoon garlic, finely chopped
1/8 teaspoon thyme, dried
1/8 teaspoon red pepper, ground
1 bay leaf
3/4 cup heavy whipping cream
2 cups whole milk
1/2 cup all-purpose flour
1 teaspoon kosher salt (sea salt OK)
1/4 teaspoon white pepper, ground

Preparation

In a medium saucepan bring the water to a boil. Add the oysters and cook for 3 minutes. Remove oysters with a slotted spoon and reserve 3 cups of liquid.
In a Dutch oven over medium heat, cook celery and onions in 1 tablespoon of butter, stirring constantly until tender. Stir in 2 1/2 cups of the reserved liquid, garlic, thyme, red pepper and bay leaf; bring to a boil. Stir in the cream. Reduce the heat and simmer 5 minutes. Stir in the milk and return to a simmer.
Melt the remaining butter in a small saucepan over low heat. Add the flour, stirring until smooth. Cook 1 minute, stirring constantly, then cook for about 3 more minutes until smooth (the mixture will be very thick).
Gradually add the flour mixture to the saucepan, stirring with a wire whisk until blended. Add oysters, salt and white pepper. Cook until thoroughly heated. Remove from heat, discard bay leaf and serve immediately.