1 pound shell-on shrimp
1 teaspoon black peppercorns
1 onion, 1 half left intact, the other chopped
3 celery stalks, 1 cut into large chunks and 2 chopped
5 garlic cloves, 3 crushed and 2 chopped
4 bay leaves
2 tablespoons vegetable oil
2 tablespoons all-purpose flour
1 green bell pepper, chopped
1 bunch scallions, chopped, white and green parts separated
2 links (about 5 1/2 ounces) andouille sausage, chopped
1 tablespoon tomato paste
Kosher salt
1 cup long-grain rice
One 15-ounce can crushed tomatoes
1 teaspoon dried thyme
Large pinch cayenne pepper
1/2 cup parsley leaves, roughly chopped
Louisiana-style hot sauce, for serving