1. Add cumin seeds, black peppercorns (and allspice if you choose) to a medium skillet and roast over medium/low heat on a stove-top. Roast until the spices become fragrant (approximately 5 minutes). Be sure to stir or toss gently to prevent scorching. Place the toasted spices in your spice grinder of choice (I like the malcojette) and grind to a powder. Note: if you have stick cinnamon (about 3" stick) you can also toast this and grind with the other spices. Be aware that this will have a bold fragrance!
2. In a medium sized bowl, combine the sugar, spices, salt and cayenne pepper. Stir or whisk to combine. You've just made a nice dry rub! Set the bowl aside to attend to the ribs.
3. Un-package the baby back ribs, pat them dry with paper towels and stage in a large sheet pan (cookie sheet). Remove the silver skin from the bone side of the 3 racks. You may need to use a paring knife to get the silver skin loose. After you find or make the opening with the paring knife, slide your fingers underneath to separate the silver skin from the ribs. You should be able to grab the silver skin and remove it like a glove once you've gotten past the first few bones.
4. Lay out a sheet of heavy duty tinfoil on the kitchen counter or worktop that is large enough to wrap the whole rack in. Place one rack of ribs on the tin foil and apply the dry rub you made earlier. Apply enough to coat all sides thoroughly. If you so choose, you can divide the rub evenly to ensure consistent application. Pour 1/3 cup of pineapple juice in the tin foil rib pack and seal tightly. The idea is to make a tin foil poaching pouch. Place each rib pouch bone side up on the sheet pan so that the pineapple juice in on the meaty side. Put the sheet pan with the ribs in the refrigerator overnight (8 to 12 hours).
5. When you are ready to cook, set your oven to 225º F. Remove the sheet pan from the refrigerator and cover with tin foil ensuring a good seal (yes. keep the ribs in the tin foil pouches). Place in the 225º F oven for 5 hours. DO NOT OPEN THAT OVEN DOOR!!!!
6. At the end of the 5 hours your kitchen will smell amazing. remove the ribs from the oven and un-package the ribs allowing them to cool. They should be incredibly tender and you can twist the bone right away from the meat.
7. While the ribs cool, heat up your grill. Once your grill is at temperature brush all sides with your favorite BBQ sauce (I like sweet baby rays). Be generous with the bbq sauce. Place the sauced ribs bone side down with the top closed for 5 to 10 minutes until the sauce has caramelized on the ribs.
8. Remove from the pit, ration out and serve!