I thought I'd post the recipe here, just in case others were curious or in need of a diet suggestion for boxers with Histiocytic Ulcerative Colitis. This is the recipe my friend used for quite some time with her boxer -- he had extremely severe HUC and she'd gone through about 20 different kibbles (incl. grainless) and nothing worked...until she stumbled on this diet... I have quoted her directly from an email to me when I asked her for the info:

HUC diet:

5 lbs of ground beef or ground turkey
1 large bag (family size or whatever) each of chopped spinach and chopped broccoli florets
4-5 sweet potatoes
2 cups of water

We brown the hamburger and drain off the fat. We put it back on the stove, add the water, the spinach and broccoli. While that is all cooking, cook the sweet potatoes in the microwave and then chop up when cooked. Add the sweet potatoes, and let the mixture stew for a while, until a sort of thick stew/gruel consistency. We usually have to use 2 large pots to cook all of it. We keep it in a tupperware container and freeze some of it, until we use the rest. We serve 1 1/2-2 cups 3x a day, and Lucky LOVES it. We also supplement with RMBs several times a week. I will say that I now actually recommend ground turkey instead of hamburger. It's less greasy, and easier to digest.
another option that worked well for her - though a bit more price-y to feed:

HomeStyle Select/ FreshPet Select Slice & Serve:

http://www.homestyleselect.com/products/slice-serve.htm

another link for good info on diets - homecooked and commercial that work well for IBD, colitis, HUC...

http://www.dogaware.com/specific.html#ibd