Inside the slow cooker, whisk together beef broth, soy sauce, coconut sugar, sesame oil, and garlic.
Place slices of beef in the liquid and toss to coat.
Cover with lid and cook on low heat for 2-4 hours, until beef is tender and cooked through.
In a small bowl, whisk together cornstarch and 1/4 cup sauce from the slow cooker.
Add the broccoli and gently toss to combine. Cover with the lid and cook 10-15 minutes or until the broccoli is tender (not mushy) and the sauce is thickened.