In a dutch oven, or extra large skillet, heat the pan over medium heat. Add in the butter and olive oil and let the butter melt and come to a slight simmer. Add in the carrots and onion, sautéing until the carrots have softened about half way through. Check them with a fork to test their doneness. Add in the broccoli florets, mixed vegetables, and chopped brisket. Stir the mixture together and then, add in the beef broth. Bring the broth to a simmer, and sprinkle with flour. With the mixture simmering, the broth should thicken slightly. When this happens, pour the mixture into a 13×9 inch casserole dish and set aside.