In the insert of the crockpot, whisk together beef consume or stock, soy sauce, dark brown sugar, sesame oil, and garlic.
Gently place your slices of beef in the liquid and toss to coat.
Turn slow cooker on low and cook for 4-6 hours. See notes below.
When done, in a small bowl, whisk together cornstarch and cooking liquid, pour into crockpot, stir to mix well. Toss in your broccoli florets. Cook on low for an additional 30 minutes to thicken up the sauce. Please see notes if your sauce does not thicken.
Serve hot over white rice.