Season the cube steaks with salt, pepper and garlic powder and set aside.
Empty the envelopes of Au Jus gravy mix and dry onion soup into the crock pot.
Pour 3 cups of beef broth to the crock pot.
Mix the cornstarch with the remaining ½ cup of beef broth until all the lumps are gone. Add it to the crock pot and stir well to mix all the gravy ingredients well.
Place the cube steak into the crock pot submerged in the liquids.
Cook on low for 4 hours or high for 3 hours. If the cube steak is thick you'll need to cook it longer.