If you order the pork from a butcher, have the rib rack reserved; use it as a roasting rack for more tender and juicy meat.
Rinse pork and pat dry. Rub mustard over it and season with the salt and pepper and place in a large nonreactive pan. Pour cider and vinegar over and refrigerate, turning often, for at least 3 hours or up to overnight.
Heat oven to 350 degrees. Let pork come to room temperature. Drain off marinade and reserve in a small saucepan.
If using, place rib rack in roasting pan; rest the pork in the curve of the bones. Otherwise, place pork directly in roasting pan.
Reduce oven temperature to 325 degrees and place pork in oven. Roast, basting with pan juices, until a meat thermometer inserted into the center of the pork reads 155 degrees to 160 degrees, about 1 hour and 40 to 50 minutes with the rack and 1 hour and 15 minutes without the rack. Test after 1 hour of cooking to make sure it does not overcook.
Meanwhile, place saucepan of marinade over medium-low heat; simmer until thick enough to coat the back of a spoon, about 1 hour; it will reduce to about 1/3 cup. Brush over pork during last 30 minutes of cooking.
Remove roast from oven and let rest for about 30 minutes.
Slice roast and layer with Green Tomato Chutney on Anadama Bread for sandwiches.