This idea came to me while food shopping one day, My local supermarket had sliced beef hearts for about a dollar a pound. Beef heart is delicious lean meat that does not have the organ-y flavor of some offal. —Jacob Kutnicki
Cloves of Garlic smashed and diced
Thinly Sliced Beef Heart (between 1/8 and 1/4 inch thick or even thinner if you can get a butcher to cut it thinner)
Large Onion (any kind is fine) cut into chunks
Sugar (use white or brown depending on preference)
Combine all ingredients in a bowl and whisk together until the sugar is dissolved.
Get a gallon sized plastic bag and put the sliced beef hearts in it. Add the combined ingredients from the bowl to the beef hearts in the bag. Try and get as much if not all the air out of the bag before you seal it. Manipulate the bag so that the marinade is evenly distributed. Marinate in the refrigerator for 1-24 hours.
Heat a frying pan or grill pan or your outdoor grill on high. Lightly oil your pan or grill pan. When it starts to give off wisps of smoke, it is hot enough. You want this pan to be screaming hot. Beef heart is best with high heat and short cook time. For a perfect medium on a 1/4 inch thick slice, you will need about 1:15-30 seconds a side, depending on how hot your cooking device actually is.
When done, place the cooked beef heart on a plate or tray and let rest for 5-10 minutes covered with foil.
Eat over rice with some lettuce; Mix in Doenjang (Korean fermented soybean paste) and some Sriracha for spice if you like. Enjoy.