Shrimp and Sausage Gumbo

Name: Shrimp and Sausage Gumbo
Ingredients: 1 pound andouille sausage (or another smoked sausage ), sliced; 1/2 cup plus 5 teaspoons vegetable oil, divided; 6 cups chicken broth; 2 (14 1/2-ounce) cans diced tomatoes; 1/2 cup all-purpose flour; 1 large onion, chopped; 1 cup chopped celery; 1 red bell pepper, chopped; 1 yellow bell pepper (or green bell pepper), chopped; 1 1/2 cups sliced okra, fresh or frozen and thawed; 1 teaspoon Creole or Cajun seasoning; 1 bay leaf; 1 to 1 1/2 pounds medium shrimp, peeled and deveined; Salt, to taste; Freshly ground black pepper, to taste; 1 teaspoon file powder, optional; 2 cups cooked hot rice, for serving; Chopped fresh parsley or green onion tops, optional