In a large Dutch oven (or large cooking pot), warm the olive oil over medium heat, along with the flour. Whisk continuously until the ‘roux’ reaches a dark caramel-esque color, about 15 minutes.
Now add in the onions, garlic and bay leaves, and stir until they’ve softened. Add the bell peppers, celery and a generous sprinkling of sea salt. Sauté for another 10 – 15 minutes, or until the vegetables are soft.
Now add in the canned tomato, veggie stock, mushrooms, spice mix, and beans. Bring to a boil and then lower the heat to medium-low and simmer for 25 minutes. Toss in the shrimp and cook for another 2-3 minutes, or until the shrimp are fully cooked through.
Serve the gumbo in a bowl over rice, with parsley and a crack of black pepper and sea salt.