I've made jerky and burgers with heart before, but my favorite by far is stew.
This is a modified family recipe that we've always called "Belgian Beef Stew", though I'm not sure how well that name applies to the paleo-ized recipe:
2 lbs bacon, diced
1 tbsp lard, tallow, bacon fat or butter (use butter if you eat dairy; it tastes the best)
2 large sweet onions, diced
6 cloves minced garlic
1 large beef heart, about 4 lbs (regular stew meat works too, of course)
4 tsp salt
1 tsp black pepper
Thickener of choice*
28 oz of dark beer or beef broth**
1 bunch parsley, chopped
Zests and juices of 2 lemons
*The original recipe calls for all-purpose flour. I usually use dried shitake mushrooms that I've ground up, but coconut flour, arrowroot starch or even cornstarch works well, too. The purpose is just to thicken, and I add it in small amounts until it's to my liking.
**The original calls for a good dark beer, and it is fantastic, so I do recommend splurging on a quality gluten-free beer, if you can handle it. Otherwise, beef broth makes a perfectly fine replacement. The thing is that it's really good with beef broth, and mind-blowingly phenomenal with beer.
First, trim the leaf fat off of your heart (I save this in the freezer and when I have enough I render it down), remove the arteries, and cube.
Over medium heat, add the bacon and preferred fat to a large pot or dutch oven and cook until browned.
Add the onions; cook until golden.
Add the garlic and cook 1-2 minutes, then remove everything from the pot and set aside, leaving some of the fat in the pot.
Add the cubed heart and brown on all sides.
Return the bacon mix to the pot along with the salt and pepper. Add the beer or broth (make sure there's enough to just cover the meat).
Bring to a boil, then reduce to a simmer and cover. Cook for at least 2 hours (the longer you cook, the better the flavor and tenderer the beef).
During the simmering, add the thickener and stir well.
Remove the pot from heat and stir in the parsley and lemon zest and juice.