frozen veggie food

I want to make some frozen veggie food for my platys. The plan is to cook, chop, and mix the ingredient (maybe with a little water), and then use a ziplock bag with a corner sniped off to squirt out little blobs on some wax paper wich I can then freeze. My question is, what ingredient can I use? I already feed them spinach, so I will be using that, but what about peas and carrots? Also, should everything be organic?