Toss the beef cubes with flour (let the excess flour come off them) and add them to the pan searing them on all their sides until well browned then remove them from the pan, about 8-10 minutes total.
Lower the heat to medium, add the carrots and bell peppers and cook for 2-3 minutes until they just start to brown then add the sesame oil, garlic and ginger, cooking for one minute while stirring well.
Add corn starch into beef broth and stir until well mixed.
Add the beef back in along with the beef broth mixture, soy sauce, brown sugar and red pepper flakes. Cook for 2 hours (up to 2:30 hours) in the oven until the beef is for tender and serve over rice or quinoa.