Combine the spices in a small bowl, then transfer to a spice jar to store
1. Preheat a large dutch oven or heavy-bottomed pot over medium heat. Add the oil, then sprinkle in the flour when the oil is hot. (Test the oil by dropping a pinch of flour in the oil; if it simmers, it is hot enough.) Toast the flour in the oil, stirring for a few minutes until it turns golden brown. Add the onion, garlic, bell pepper, celery, and salt and stir. Sauté on medium until the onion is translucent, about 3 minutes. Add the diced tomatoes, stock, bay leaf, dulse, Creole Seasoning, and Old Bay seasoning. Stir well and bring the pot to a simmer. Add the mushrooms and continue to simmer for 20 minutes until they become tender.
2. Taste for seasoning and add more Old Bay seasoning if desired. Serve over rice with a squeeze of lemon juice and garnished with parsley.