Shrimp And Sausage Gumbo

Name: Shrimp And Sausage Gumbo
Ingredients: 2 tablespoons vegetable oil; 1 red bell pepper, cut into 3/4-inch pieces; 1 medium onion, coarsely chopped; 1 celery rib, cut into 1/2-inch pieces; 2 garlic cloves, very finely chopped; 1/4 teaspoon cayenne pepper; Salt and freshly ground pepper; 1/2 pound andouille sausage or spicy kielbasa, halved lengthwise and sliced crosswise 1/2 inch thick; 2 tablespoons all-purpose flour; 4 cups chicken stock or canned low-sodium broth; 2 thyme sprigs; 3/4 pound shelled and deveined medium shrimp; 1 scallion, thinly sliced; 1 tablespoon finely chopped flat-leaf parsley