No you didn't suggest fish to someone who is already concerneda bout artificial flavors, fish has mercury, but I guess we have to survive somehow, eat or die...
How about buying bulk protein powder at a store that specialized in this - nutrition store etc, Whole Foods might even have organic protein based on soy, so mixed that up, chill it well, and it's good for a day or two.
I am sure you know we need essential fatty acids, so flax seed oil, fish oil, omegas... need I go on?