If you can’t find the pre-sliced stir-fry beef strips, you can buy a 2 pound chuck roast or flank steak and slice it yourself into the thin strips. *Tip – if you partially freeze the beef it will be easier to thinly slice.
Place beef broth, soy sauce, brown sugar, sesame oil and garlic into slow cooker and combine well. Add meat and give it all a good mix.
Cook on low for 3 hours (or high for 1 1/2).
In a small bowl, combine ½ cup of the liquid from the slow cooker with the cornstarch. Whisk until smooth.
Pour cornstarch mixture back into the slow cooker and stir. Cook for another 30 minutes. The sauce will thicken during this time.
At this point you can add your frozen broccoli to the slow cooker (at the same time you add the cornstarch) or you can cook your broccoli separately. If you cook the broccoli separately, simply add the it into the sauce before serving so they're covered in that saucy goodness.
Serve over rice.