First, of course, is procurement.
It is best to use what is on hand, as this increases the uniqueness of the dish, and encourages substitution and creativity. A heart you can get from your local butcher, if you trust him (always a him, the butcher).
The younger and fresher the heart, the more tender.
A heart is a strange meat. Rarely eaten except ritually or in times of great stress; it has too many connotations with life and death, and, since it is always beating, has a reputation for toughness.
You should find a fresh, young heart - preferably veal, or lamb. Kid might work, too, if you live in the right neighborhood.
Unwrap the heart carefully - as tough as they are, they can be delicate, and you may not get another chance. Be sure to drain and rinse before using, and never, never freeze.
Marinate the heart in the traditional spices and liquids: vinegar, alcohol, herbs, salt and pepper. Depending on the age and toughness, and your own preference, other spices may be added. You prefer a plastic bag, with the ingredients added and the air squeezed out. Don't bother measuring - add acid, oil and heat by sight, by smell, by color. Don't bother using the wine you will serve with a meal - you know that is an old wives' tale. But don't use a wine you wouldn't drink alone.
Since the meat is so tough, you decide on a slow low-heat method. Braising should work well.
On the stove, turn the gas (you do have gas, yes? Or maybe one of those fancy induction ranges? No, gas.) to medium. Get a heavy casserole dish, with a tight-fitting lid. Preheat the oven to standard cooking temperature, and put the dish on the range. Remove the heart from the marinade, and place in the oiled, now hot, casserole.
You are careful to keep the heart moving. You should think about side dishes, in keeping with the theme of the meal. Root vegetables, simple greens. No dessert. Perhaps cooked fruit, or a simple slice of excellent brown bread?
Keep the flavors simple and light: the heart is the focus of the meal.
You remember the turnips in the fridge, or the carrots, or the apples and pears. You'll think of something. You always do.
The heart should be done searing by now, those lovely Maillard reactions browning the surface and filling the kitchen with a mouth-watering smell. Flip the heart over, and continue browning. Add sliced garlic and onions, carrots perhaps or other aromatic vegetables. Make sure to soften them, as in a mirepoix or soffrito.
You never could understand why the two terms, two techniques, for things so close in aim and execution. You blame Catherine de Medici.
You should find the ingredients for your side dishes now.
And now you remove the heart from the range. Add stock, wine, and spices. Perhaps fennel and coriander, for a Mediterranean slant, or turmeric and cinnamon and allspice, for something farther from home.
Slide the casserole dish into the oven. The heart will take a while to cook. You need to consult your wine cellar (cabinet, refrigerator, box?) and pick a wine.
The Bordeaux? The Shiraz? The Cabernet Sauvignon from Napa, or that tempting Super Tuscan?
The Cotes du Rhone. Full of promise, that one.
While the heart cooks, prepare the side dishes. Seasonally is best, whether around Mother's day, Christmas or the autumnal equinox. Each has it's own flavors. Trust your decisions, regarding your heart. Here, the only flaw is hesitancy. What did you see this morning? Chicks nesting, or flying off? Leaves unfurling, the riot of summer, the promise of winter?
After some time (you should know when it is right, but to prevent guessing, use a thermometer. Be sure to jab deeply) remove the heart. Let rest on the sideboard before carving, while you arrange your sundries on the plate. Decant the wine, slip some into a glass, and savor.
The Cotes du Rhone. Not as good as you had hoped? Certainly not as good as your memory.
Slice thinly, your heart, and enjoy. Be sure to break up the flavors with your wine, your garnishes. You don't want to eat it all at once.
You might get sick.