Heart is a familiar muscle meat, yet also a hard-working nutrient-dense organ. I think that it’s a really accessible way to start eating organs since the texture of muscle meat is familiar and the flavor is not as intense as liver or kidney. That said, working muscles do have more flavor in general, like dark meat versus light meat in poultry.
As always, the smaller animals have milder organs. Grilled chicken hearts are kind of like candy. After you get them to try just one, I’ve seen kids that would probably never otherwise eat organ meats sneak them from the serving dish.
Heart should be smooth and firm when fresh.
As McGee describes in On Food and Cooking, “the nonskeletal muscles – stomach, intestines, heart, and tongue – generally contain much more connective tissue than ordinary meats – up to three times as much – and benefit from slow, moist cooking to dissolve the collagen.” (p. 167)
In discussing similar properties in squid and octopus, he notes that the meat
“…must be cooked either barely and briefly to prevent the muscle fibers from toughening, or for a long time to break down the collagen. Cooked quickly to 130-135F/55-57C, their flesh is moist and almost crisp. At 140F/60C it curls and shrinks as the collagen layers contract and squeeze moisture from the muscle fibers. Continued gentle simmering for an hour or more will dissolve the tough, contracted collagen into gelatin and give the flesh a silken succulence. Pounding can also help disorganize and thus tenderize…” (p. 230)
Preparing heart is pretty simple. Trim ventricles or any fibrous tissue and remove any excess blood.
For a poultry heart, just snip off the top portion with the connecting tubes. Then, flip the heart upside-down and squeeze a bit over a paper towel. If there is any excess blood clots, they’ll squeeze out.
For larger hearts – like lamb or beef – wash thoroughly to remove any blood. There is no need to soak the heart. Remove hard arteries or connective tissue with a knife.
Lamb or goat hearts can be served whole. For a beef heart, cut lengthwise to open it. Remove the fibrous connective tubes within and any silverskin – silvery connective tissue that won’t break down when cooking. After opening, cut additional strips lengthwise against the grain.
As for the fat on the exterior (especially on beef heart)…well, there is some debate on this. Looking for an even clean cut of meat, some sources recommend removing these white fat patches. For example, this is recommended for making even cubes for grilling. Or preparing a medium-rare ‘steak’ – albeit one that costs less and has more nutrients (particularly folate and other B-vitamins and minerals).
However, the heart is a dense, low-fat organ, so preserving the fat can add some moisture, especially if cooking slow and low. If you do remove the fat, be sure to save it and use as the base of your dish or later.
That said, heart benefits from the extra moisture delivered from salting or brining in advance of cooking.