4 racks (2 1/2-pounds each) pork baby back ribs
To prepare the spice rub: The day before you cook the ribs, make the spice rub. In a medium bowl, mix the brown sugar, paprika, black pepper, salt, cayenne pepper, and cumin together. Place the ribs on 2 large baking sheets, and rub the ribs all over with the spice mixture. Cover, and refrigerate for at least 4 hours and up to 24 hours.
To make the barbecue sauce: In a large saucepan, heat the oil over medium heat. Add the onion, and cook, stirring often, for about 5 minutes, or until tender. Stir in the garlic, and cook for about 3 minutes, or until the garlic is tender. Stir in the paprika, then stir in the whiskey and vinegar, bring just to a simmer, and cook for 3 minutes. Stir in the broth, ketchup, honey, worcestershire sauce, mustard, salt, black pepper, and cayenne. Bring the sauce to a simmer over high heat. Reduce the heat to medium-low, and simmer uncovered, stirring often to prevent scorching, for about 30 minutes, or until the sauce reduces and thickens slightly. Remove from the heat.
To bake ribs: Position the racks in the center and upper third of the oven, and preheat the oven to 375°F. Cover the ribs on the baking sheets with foil. Roast the ribs for 45 minutes. Rotate the baking sheets, and baste the ribs with barbecue sauce, and re-cover them with foil. Roast an additional 1 1/2 hours, or until the ribs are tender and the meat has shrunk from the ends of the bones. For the last 10 minutes of cooking, uncover the ribs, baste them with the barbecue sauce every few minutes or so, allowing the sauce to set before applying the next coat.
Using a large sharp knife, cut the racks into individual ribs. Arrange the ribs on a platter, and serve with the remaining sauce on the side.