Preheat oven to 375˚F. Sprinkle brisket on both sides with five-spice, salt, and pepper. Set brisket in a 9x13-inch baking dish, with the side trimmed of fat facing up). Place the shallots and satsumas on and around the brisket. Roast, uncovered, for 30 minutes.
Whisk together the beef broth, balsamic vinegar, and arrowroot powder in a bowl or measuring cup with a spout. Whisk until arrowroot is fully dissolved. Remove the brisket, and pour the broth mixture into the baking dish. Cover tightly with aluminum foil, and continue to cook about 3 hours, until the brisket is very tender.
Allow to sit at room temperature for 30 minutes. Transfer the brisket to a cutting board, and slice against the grain. Serve brisket with Satsuma-shallot mixture ladled on top.