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. If using andouille sausage add them now. Add the garlic and bay leaves. Continue to cook for an additional 1-2 minutes until the garlic is nice and fragrant.