I did every other chore I needed to get done for the evening to let the heart marinate for as long as possible. When I ran out of other chores and my stomach was growling too loudly to ignore I pulled the heart out of the marinade, salt and peppered it and fired it in a hot cast iron skilled with a couple tablespoons of oil.
Chris recommended a high heat to caramelize the heart. About 3 minutes per side to end up with medium cooked. It came out perfect. I expected the heart to be a bit tough and chewy. It was neither. It definitely had a different texture from a steak, or even from the venison heart I remember eating, but it was more like a lean steak then you would think. Which makes sense. A heart is a muscle. It's not like other organ meats, it's much more similar to the steak we're use to eating, minus the fat. The marinade definitely tenderized it, even in the short time I had. The heart was tender and lean, and had no hint of gaminess. The leftovers made a delicious heart sandwich the next day. I will be buying more heart ( at a couple bucks for a pound of meat it's worth it) and I can't wait to do Chris's marinade for the full 3 hours. It was delicious with the short time I had, I can only imagine how good it will be when done properly.