Preheat the oven to 325° F. Position a rack in the lower third of the oven.

Meanwhile, use a mortar and pestle or spice grinder to coarsely crush the fennel seeds. Set aside 1 tablespoon, then transfer the remaining fennel to a medium bowl and add the honey, mustard, and pepper. Set 1 1/2 cups of the mixture aside.

Place the ham flat side down in a large shallow roasting pan and brush with about 1/2 of the remaining honey-mustard mixture. Roast the ham, basting with the same honey-mustard mixture and pan juices every 25 to 30 minutes, until the internal temperature reaches 140° F., 15 to 18 minutes per pound (loosely cover with foil if ham gets too browned). Remove the ham from the oven, transfer to a cutting board, and let rest 15 to 30 minutes.

Meanwhile, add a rack to the upper third of the oven and increase the temperature to 400° F. Arrange the asparagus on two large rimmed baking sheets. Drizzle with the olive oil, sprinkle with salt and reserved fennel seeds, and bake until tender, about 15 minutes.

Slice enough ham to serve and arrange on plates or a platter. Serve the asparagus and the reserved honey-mustard mixture on the side.