Mix up broth, soy sauce, sesame oil and brown sugar and pour over beef. Cover and cook on low for 3 hours until meat is tender.
Remove about 1/4 cup of the liquid from the slow cooker and whisk cornstarch into it. Return the mixture to the slow cooker and stir. Add broccoli and replace lid.
Increase heat to high and cook for another 20 minutes or until broccoli is tender. Season to taste with salt and pepper and serve!