I havn't tried pork kidneys, but I have some beef in the freezer. Mine came already prepared from the butcher, all I had to do was cook them up. I sautee'd them in a little butter and olive oil, then I added some tomato paste, and worchester sauce and then stired through some cream. I found the flavour very strong, and only managed a small amount. I can see why they are traditionally eaten on toast as you need something a little bland to go along with them. They might be good in a stirfry? Or with steak as part of a casserole, thats my plan for next time.