Heat vegetable oil in a large, heavy-bottomed pot over medium heat. Gradually whisk in flour, stirring constantly. Cook for 20-30 minutes until roux turns deep chocolate brown.
Add chopped onion, bell pepper, celery, and garlic to the roux. Cook for 5-7 minutes, stirring frequently, until vegetables soften.
Stir in diced tomatoes and cook for another 2-3 minutes.
Slowly pour in seafood stock, stirring well to incorporate the roux. Add bay leaves and Cajun seasoning.
Bring to a gentle simmer and cook for 20-25 minutes, stirring occasionally.
Stir in sliced andouille sausage and cook for 10 minutes. Add shrimp and crab meat, simmering for 5-7 minutes until shrimp are pink.
Season with salt and pepper. Remove bay leaves before serving.
Ladle gumbo over cooked rice and garnish with chopped green onions.
Preparation time: 15 minutes Cooking time: 1 hour Total time: 1 hour 15 minutes
Calories: ~425 kcal per serving
Servings: 6-8
