Step 1In a medium saute pan heated over medium heat, toast the fennel and coriander seeds until aromatic, about 2 minutes. Remove from heat and cool completely.
Step 2Grind the fennel and coriander seeds to a fine powder using a spice mill or coffee grinder, then combine with the ginger, nutmeg, paprika, salt, black pepper and cayenne powder to form a rub.
Step 3This makes a generous 1 cup rub, and you may not use all of it for the final recipe. Store the rub in an airtight jar or sealable plastic bag in a cool, dark place up to 4 to 6 weeks.
Step 1Coat the rib racks generously on each side with the spice rub. Refrigerate, uncovered, overnight to season.
Step 2The next day, in a large saucepan, bring the cider, chicken and beef broths and bay leaves to a boil over high heat. Remove from heat and season with salt and pepper to taste.
Step 3Heat the oven to the broiler setting. Place the rib racks on a rack over a rimmed baking sheet. Broil the racks until browned on each side, about 2 to 4 minutes per side, depending on the heat of the broiler.
Step 4Reduce the oven heat to 300 degrees. In a large roasting pan, combine the diced apples, onion, carrots and celery heart, and place the seared ribs on top (pour any drippings from the rimmed baking sheet over the ribs). Pour over the hot broth.
Step 5Cover the pan tightly, first with parchment paper, then a layer of plastic wrap, then with a layer of foil, creating as tight a seal as possible. Place the covered pan in the oven and braise the ribs for 3 hours.
Step 6Remove the pan from the oven and cool the ribs completely. Skim the fat from the pan and set the ribs aside. Strain the braising liquid (we had about 1 quart) into a saucepan and bring to a boil over high heat. Reduce the sauce by half.
Step 7To reheat the ribs, place the ribs in a roasting pan and pour the sauce over. Place the ribs in a 325-degree oven and heat until the ribs are warmed through before serving.