ROUX: Heat the oil in a large dutch oven or a heavy bottom pot over medium-high heat. Whisk in the flour until combined and smooth. Switch to a wooden spoon and continuously stir for 15-22 minutes or until the roux darkens to just past a deep peanut butter color. Take your time here and don't be tempted to crank up the heat. You do not want to let the roux burn! (if you smell it burning, you will need to throw is out, clean the pot, and start over, unfortunately there's just no saving burnt roux!)
SAUTE: Once the roux reaches that deep rich brown color, stir in the onions, bell peppers, and celery and continue to cook, stirring as needed so the vegetables don't stick. About 8-10 minutes or until the veggies soften. Add the garlic, andouille sausage (if using tofurky, do not add yet, you'll need to brown it in a skillet first then add it with the shrimp at the end), and bay leaves. Continue to cook for an additional 1-2 minutes until the garlic is nice and fragrant.
SEASON: Add the cajun seasoning, tabasco sauce, and cayenne along with the chicken broth and stewed tomatoes (if using) and bring to a high simmer before lowering the heat to medium-low, covering and simmering for 15-20 minutes.
ADD PROTEIN: Add the shrimp and sausage (if using) to the gumbo, give it a stir and allow to continue to simmer for an additional 10-15 minutes or until the shrimp is opaque and the veggies have softened. Taste and season with salt and pepper as desired. Add the gumbo filé and stir. Remove bay leaves before serving.
TO SERVE: Serve warm with white rice or quinoa with sliced scallions on top.