Going back over the archives I wanted to add to this thread.
The last couple of ox hearts cooked up for humans were cooked in the slow cooker, before going in the oven for the last 10 minutes or so. What's left in the slow cooker is used as a stock, usually for a bean based stew or such like. The heart is eaten as a roast and the left overs sliced up and consumed in sandwiches by dave. He's disappointed every single time I bring an ox heart home and tell him that it's for the dog.
If there's anyone reading this who hasn't tried heart before - give it a ago. Go to a butcher and buy it from there because supermarkets over charge you and cut it up for you, giving you no choice. It's cheap, it goes a long way, and it tastes alright. My local butcher does a very good price on ox heart so saturday I bought enough meat for several meals all for the costly sum of £3.28.