Position a rack in the lower third of the oven and heat the oven to 325 degrees F. Trim away any skin and external fat to a thickness of about 1/4 inch. Set the ham fat side up and score the fat 1/4 inch deep with diagonal slices every 2 inches so that it forms a cross-hatched diamond pattern.

In a medium bowl, combine the tea, cider and 1/4 cup of the maple syrup. Set the ham in a sturdy roasting pan or a baking dish. It should fit fairly snugly with only a couple of inches of space on any side. Add the tea-cider mixture, plus enough water to reach a 1/4-inch depth. Bake, adding water as needed to maintain 1/4 inch of liquid in the pan, until an instant-read thermometer inserted into the center of the ham registers 105 degrees F to 110 degrees F, 1-3/4 to 2-1/4 hours (it should take about 15 minutes per pound).

In a small bowl, mix 2 tablespoons of the maple syrup with the brown sugar and cardamom to make a thick, wet paste. Remove the ham from the oven and raise the temperature to 425 degrees F. Add more water to the pan so the liquid is about 1/2 inch deep. Using a spatula or your fingers, smear the maple-brown sugar mixture generously over the top of the ham. Return the pan to the oven (even if it hasn't reached 425 degrees F yet) and bake until the glaze on the ham bubbles and begins to darken, 10 to 15 minutes; the ham should have an internal temperature of 120 degrees to 125 degrees F.

Remove the ham from the oven and transfer to a carving board or large platter. Tent loosely with foil and let rest for 20 to 30 minutes while you make the pan sauce. During this period, the ham's internal temperature should rise to 130 degrees F to 140 degrees F.

Pour the pan juices into a gravy separator or a 4-cup Pyrex measuring cup. Let sit for 10 to 15 minutes to allow any fat to rise and then pour or spoon off the fat and discard (some hams don't exude much fat).

Pour the pan juices into a 2-quarts saucepan, whisk in the remaining 2 tablespoons maple syrup and the vinegar, and bring to a boil. Taste the sauce, and if the flavor isn't as intense as you'd like, continue to boil to concentrate the flavors as desired.

Stir in about half the cornstarch mixture (called a slurry), and whisk until the sauce thickens slightly, about 15 seconds. Add more of the slurry for a thicker sauce. Set aside and keep warm while the ham rests.

Leftovers: Fry up any leftover ham and serve it with Redeye Gravy. The leftover ham bone is perfect for flavoring a big pot of collard greens.