This Creole gumbo is a soul-warming ode to seafood

Ingredients

• 4 quarts shrimp stock (recipe follows)
• 1 cup vegetable oil
• 1 cup all-purpose flour
• 1 large onion, finely chopped
• 3 ribs celery, finely chopped
• 1/3 pounds smoked sausage, sliced
• 1 pound frozen gumbo crabs, defrosted
• Salt and pepper or Creole seasoning
• 2 pounds Gulf shrimp, peeled
• 1/2 pounds claw crabmeat
• 1 pint Gulf oysters
• 1/2 cup chopped parsley
• 1/2 sliced green onions (white and green parts)
• 1 tablespoon filé powder or more to taste
• Heads and shells from 2 pounds fresh Gulf shrimp
• 1 large onion, halved
• 2 ribs celery, coarsely chopped
• 2 bay leaves
• 10 black peppercorns, crushed
• 1 gallon cold water