1) Combine all of the rub spices in a small bowl. Brush both sides of the rib racks with oil and rub with the spice mixture. Wrap in cling film and refrigerate for at least 12 hours.
2) In a large saucepan over low heat, add all of the mop ingredients. Bring to a simmer and cook until the sugar is dissolved. Let cool to room temperature.
3) Remove the ribs from the refrigerator 45 minutes before smoking to allow them to come to room temperature. Add the mix of hickory and applewood chips to the smoker according to package instructions. Heat a smoker to 105C. Put the apple cider in a small heatproof pan in the smoker.
4) Put the ribs directly on the smoker rack. Smoke for 6 hours, brushing the ribs with the mop every hour for the first 5 hours. During the last hour, brush the ribs with the BBQ sauce every 10 minutes.
Remove the ribs to a serving platter and serve.
1) Heat the oil over medium-high heat in a heavy-bottomed medium saucepan. Add the onions and cook until soft, 3 to 4 minutes. Add the garlic and cook for 1 minute. Stir in the tomato ketchup and water, bring to a boil and simmer for 5 minutes.
2) Add the remaining ingredients and simmer until thickened, stirring occasionally, for about 10 minutes. Cool for about 5 minutes.
3) Carefully transfer the mixture to a food processor and puree until smooth. Season with salt and pepper, to taste, then pour into a bowl and allow to cool at room temperature.
The sauce will keep for one week in the refrigerator, stored in a tightly sealed container.