Place the sliced or cubed steak into the slow cooker.
In a large bowl, whisk together the beef broth, soy sauce, hoisin sauce, garlic, brown sugar, sesame oil, salt, and pepper.
Pour the sauce over the steak, then gently toss to coat all of the steak on all sides, in the sauce.
Place the lid on the slow cooker and cook on low for 5-6 hours or on high for 3 hours.
Just before the cooking time is up, whisk together the cornstarch and water in a small bowl to create the cornstarch slurry.
When the cooking time is complete, switch the heat level to Keep Warm. Add the cornstarch into the steak and sauce in the slow cooker. Gently stir and combine until there are no white clumps visible and the slurry has dissolved into the sauce.
Add the frozen broccoli and gently toss with the beef. With the heat on Keep Warm, allow the broccoli to heat up in the slow cooker until it's heated through, about 5 minutes.
Serve over rice and garnish with sliced green onions and sesame seeds, if desired.
Notes
Makes approximately 5-6 servings.Storage: Allow the beef to cool down, then store in an airtight container in the refrigerator for up to 3 days.