Some friend and I tried some beef heart in a Chinese sauce, and another time in some chipotle sauce; also the same things with pork hearts (things we used to get at Asian markets, where they carried every kind of offal!). The beef heart we cooked longer, until tender; now I'd pressure cook it in my Instant Pot, before cooking the syrupy sauce down. The Chinese one I cut into 3/4" cubes, and based it on 1,2,3,4,5 spareribs, with a tsp of 5 spice powder in it. The chipotle dish I based on an old chuck roast dish in an old Diana Kennedy dish, in which the beef was cooked whole, until tender, in seasoned water, and the beef is diced up (about 1/2", or a little smaller, for wrapping in tortillas), and the sauce is made with the cooking water, with dried chipotles or moritas. The sauce is "fried" about 7 minutes, then the rest of the broth is added, along with the heart, and simmered another 20 minutes.