I pickle my deer hearts. Seems we never have enough to go around twice.

Boil heart with 2 bay leaves until tender (about 2hrs)
Slice, cool and put in brime.
Brime: 1 part vinager 3 parts water (I use water I cooked heart in)
1 med onion sliced
salt and pepper to taste
refrigrate until lunch next day
serve on bread, with spicy mustard.