Shrimp and Andouille Gumbo

INGREDIENTS

• 1/2 cup vegetable oil
• 1/2 cup all-purpose flour
• 1 small cup onion, minced (about 1/2 cup)
• 1 small green bell pepper, minced (about 1/2 cup)
• 2 stalks celery, minced (about 1/2 cup)
• 1 quart chicken stock or low-sodium broth
• 2 bay leaves
• 1/2 pound shrimp, peeled, deveined, and cut into 1/2-inch dice
• 1/4 pound andouille sausage, cut into 1/2-inch-thick rounds
• 1/2 pound fresh okra, trimmed and cut into 1/2-inch-thick rounds
• 1/2 teaspoon salt
• 1/2 teaspoon cayenne pepper
• 1/4 teaspoon freshly ground black pepper
• 4 cups cooked white rice
• Hot pepper sauce, such as Tabasco
• About 2 teaspoons filé powder