Toast the fennel, coriander and cumin seeds in a sauté pan until fragrant and oils have been released. Grind in a spice grinder until in powder form. Feel free to use ground spices if you prefer, but use a 1/2 tsp LESS of each.
Remove the thin, papery membrane from the back of each rack by inserting a knife under it. The best place to start is on one of the middle bones. Using a paper towel, or pliers to secure a grip and peel off the membrane.
In a small bowl whisk together the toasted/ground spices and all the remaining dry rub ingredients and rub all over ribs. Wrap the ribs back up in the butcher's paper (it has a great wax interior side to keep juices from dripping out), and seal with aluminum foil. Place in the refrigerator for 24 hours.
Set up the grill and preheat to medium (325° to 350°F).
Unwrap the ribs and place on a rack inside a large roasting pan or aluminum foil to catch drips and avoid flare ups.
Place the ribs, bone side down, in the center of the grate, cover the grill and cook the ribs for 45 minutes.
In a small bowl add the melted butter, apple cider vinegar or apple juice and soy sauce. Mix together and set aside.
Mop the ribs on both sides with the mop sauce. Re-cover the grill and continue cooking the ribs until well browned, cooked through, and tender enough to pull apart with your fingers, 45 minutes to 1 hour longer. Baste often with Mop Sauce.
If you are not using whole spices, use a 1/2 tsp LESS of each ground spice.
For a sweeter mop sauce substitute apple juice for the apple cider vinegar.