Cooked diet for Mini Schnauzer prone to bladder stones?

[RemRem]

Would anyone have any menu suggestions for a cooked diet for my miniature schnauzer who may be developing bladder stones. He's previously been on only dry food, which I have discovered unfortunately was not of the best quality. Vet says he should really be on a moist diet to increase his water intake. I've looked into some of the better commercial brands of canned food, and based on the ingredients it looks like I could surely cook him up something at home as good or better! I did do a couple of basic recipes one with poached chicken breast and other with ground beef, mixing 1/2 meat with 1/3 cooked brown rice and a small handful of oatmeal and frozen mixed veggies thrown in and cooked together. I'm looking for any recommendations for any different ingredients or additives or ingredients to avoid, especially for his urinary condition. Thanks!