For the Roux:

• 1/2 cup vegetable oil
• 1/2 cup all-purpose flour

For the Gumbo:

• 1 large onion, diced
• 1 green bell pepper, diced
• 2 celery stalks, diced
• 4 cloves garlic, minced
• 1 pound andouille sausage, sliced
• 1 pound boneless skinless chicken thighs, cut into chunks
• 1 teaspoon salt
• 1/2 teaspoon black pepper
• 1 tablespoon Cajun seasoning
• 1/2 teaspoon dried thyme
• 1 bay leaf
• 6 cups chicken broth
• 1 (14.5-ounce) can diced tomatoes (optional)
• 1 tablespoon Worcestershire sauce
• 2 cups cooked white rice
• Chopped green onions and fresh parsley for garnish