It isn't hard without food, but if you haven't tried this yet, your dogs are missing out!
It's cheap and easy, all you need to do is buy chicken gizzards and hearts (ewww, gross I know). I get them for a buck fifty. Put them in the crock pot with some water (small crock pot for one pack) and cook overnight. Since I have eleventy billion dogs, I will take the broth and mix it with your dog's food as it makes a gravy type substance with it. The organs are the icing to the proverbial cake. My pack loses their minds for this, and fussy eaters will lick the bowls and then go around licking other bowls clean, hoping that someone didn't get it all.
Cheap treat, BIG rewards.