This is so simple you are going to slap yourself for not thinking of it first.
I know I did!
1. Go to the market, and pick up some organic baby foods with simple ingredients like Sweet Potato, Apple, Peas, Banana...
2. Remove lid and empty into Kong (or if you trust your dog, just freeze in the glass jar)
3. Freeze for 8-12 hours
4. Give to your dog