Start by making the gluten-free roux. Heat the oil in a large Dutch oven or heavy-bottomed pot on medium for 1-2 minutes. Stir in the chickpea flour and continue stirring often until there are no clumps and the mixture turns to a dark brown caramel color, about 5 minutes.
Quickly add the onion, green pepper, celery, and jalapeños, stirring, and cook until vegetables start to soften and onions become translucent, about 4 minutes. Add the garlic and cook for another minute.
Slowly add the vegetable stock, a little at a time, stirring until the roux fully incorporates with the stock, then add a little more stock. Repeat until all stock has been incorporated.
Add the bay leaves, lemon juice, tomatoes, Cajun seasoning, cayenne pepper, smoked paprika, and salt and pepper. Stir in the mushrooms. Cover and cook on low for about 10 minutes.
Serve hot over rice. Add hot sauce as desired.