Place the beef, bell peppers and onions in a slow cooker.
Add the seasonings, brown sugar, and soy sauce over the beef and peppers.
Pour the beef broth in the crock pot.
Stir to combine.
Cover and cook on low for 5-6 hours or on high for 2.5-3 hours until the steak is cooked through.
In a small bowl, whisk together the cornstarch and cold water.
Stir this mixture into the crock pot. Cook on high for 30-60 minutes until the sauce has thickened.
Serve over white rice.