A lot of my neighbours come from some part of Europe long time ago. I often chit chat with one lady who comes from some German- and French-speaking countries.
And she said where she comes from ppl eat stuff inside animals.
And here is the way she cooks beef heart.
Slice it to chunky pieces then marinate in salt, pepper and flour.
Heat the pan very hot with butter then add beef heart, then onion, then carrot and potato, then some beef broth, red wine and dried-thyme.
When i asked her what she served with, she said Bread.