Trim the beef heart - removing excess fat (you can save it and cook with it - waste not want not!) but leave some in as it creates a nice richness. Remove the extra membranes and silverskin on the meat before cubing it and placing in the slow cooker.
On top of the meat, add salt, fresh black pepper, bay leaves, and dried parsley. I chose to make this first stew as simply spiced as possible, but it would also be very good with other traditional herbs added. Considering how well this turned out, I will be exploring all kinds of flavor options.
Cube the vegetables and add to the top of the meat. Add in water, cover and cook 8 hours on low or 5-6 hours on high. If going for the low setting, if it cooks a little longer than 8 hours that's usually ok too as long as there's enough water. Enjoy!
Make ahead and reheat too - I don't use microwaves, but this reheats well on the stovetop.