In a mixing bowl, combine beef broth, soy sauce, brown sugar, sesame oil, sriracha, ginger, garlic and green onions.
Add steak to bottom of a large slow cooker. Pour broth mixture over steak and stir well.
Cover and cook on low 4 hours.
When steak is tender, spoon a few tablespoons of broth from the slow cooker to a small bowl; whisk in cornstarch to make a slurry. Pour into slow cooker and toss with beef until combined.
Stir in broccoli, cover and cook an additional 15-20 minutes.
Serve over rice and garnish with sesame seeds and green onions, if desired.