Some people may say this recipe is missing flour. I will respectfully disagree. First, I really dislike adding flour to my sauces, there's no such rule that beef casserole or a beef stew needs a thickening agent. As the soup simmers, the juices will reduce beautifully and the potatoes will give off plenty of that needed starch, creating some of the most velvety broth you've ever had. I do avoid adding unnecessary carbs to my dishes but you may feel free to add a spoonful of flour or cornflour and if you chose to, add it at the beginning just before adding the liquid. If you do choose to add flour, increase the liquid amount by a cup or two.