Since the heart of an animal is a well-used and hard-working muscle, it tends to be tough and is therefore best braised or stewed with plenty of vegetables. In fact the heart makes a natural container for a breadcrumb and herb, or sausagemeat, mixture. It can be roasted, plain or stuffed.
Veal and lamb hearts are the best; beef heart is larger, can take three to four hours to become tender, and should be cooked in plenty of liquid. Heart from younger animals takes two to three hours.