I too would avoid the stock cube. I also agree about the rice - wholegrain is more nutritious but make sure you cook it very well. You have three types of carbohydrate in the recipe - barley, rice and white potato. I am not sure that you need so many. Sweet potato has more nutrients so I would be inclined to substitute with that.
You need to add some sort of oil because dogs need fat for health. There is an article here
about this. Also, as Tinyplanets has said, calcium supplementation is a necessity if your dog doesn't have bones. I don't know the exact amount but it can be provided by tablet, dried, ground eggshells, bone meal. There is an all round vitamin supplement called SF50
that contains calcium.
To make it easier for yourself, you might want to consider Pure Pet Foods Vegi Plus Mixer because it has the required additives and all you have to do is add the protein and any extra fruit and vegetables. Also, We Cook for Dogs
would be worth thinking about because they sell the necessary supplements and provide advice/recipes for you to cook your dog's food at home.