For the spice rub and mop: Mix spice rub together in small bowl. Stir cider and vinegar together in small saucepan. One hour before cooking ribs: Place wood chips in bowl with enough water to cover. Reserve 2 tablespoons plus 1 teaspoon spice rub. With fingers, work remaining rub into both sides of rib racks. Let ribs stand at room temperature until ready to cook. Fifteen minutes before cooking ribs: Transfer soaked wood chips to small disposable aluminum pan. Place pan directly on primary burner in grill, turn all burners to high, and preheat with lid down until chips are smoking heavily, 15 minutes. Turn primary burner down to medium and shut off other burners. Position ribs over cool part of grill. Cover grill, positioning lid so that vents are opposite wood chips to draw smoke through grill. Meanwhile, bring mop to simmer; cover and keep warm. Barbecue ribs until meat starts to pull away from bones and has rosy glow on exterior, 3 to 4 hours. You will need to flip ribs and baste them with mop. At all other times, keep grill covered. Before removing ribs from grill, sprinkle each rack with 1 tablespoon reserved spice rub. Remove pan with wood chips from grill. One at a time, place each rack of ribs on hot burner, cooking about 30 seconds on each side, then transfer to cutting board. Tent ribs with foil and let rest for 20 to 30 minutes. While ribs rest, add remaining 1 teaspoon spice rub to remaining mop and simmer, uncovered, until liquid has reduced to about 2 cups, 10 to 15 minutes. Add Tabasco and more salt and pepper to taste, if desired. Slice ribs between bones and serve with sauce on side.