Preparation

• Heat the oven to 350°F. Combine the cumin, mustard, and coriander. With your hands, pat the spices all over the pork loin. Sprinkle with salt and pepper. Heat the olive oil in an ovenproof, heavy-based pan over medium-high heat. When the oil is hot, add the pork and sear it on all sides. Put the pan in the oven and roast the loin until a meat thermometer registers 145°F, 40 to 50 minutes.  (The pork will continue to cook out of the oven.) Let cool.
• Cut the cooled pork loin into thin slices. For each sandwich, spread a generous amount of apple butter on one slice of the bread; spread the mustard on the other. Pile the slices of pork on one side and top with the other.