How to Make It
Preheat oven to 475°F.
Crush peppercorns and coriander seeds with a mortar and pestle or small heavy skillet until coarsely ground. Combine with 3/4 teaspoon salt in a small bowl. Spread mustard evenly over pork; coat with spice mixture.
Heat 2 tablespoons oil in a large nonstick skillet over medium-high. Add pork; cook 5 minutes, turning to brown on all sides. Place pork and potatoes on a parchment paper–lined baking sheet; drizzle with drippings from skillet. Bake at 475°F for 10 to 12 minutes or until a meat thermometer inserted in center of pork registers 145°F. Let pork stand 5 minutes. Cut across the grain into slices.
Combine remaining 1/4 teaspoon salt, remaining 1 tablespoon oil, yogurt, cilantro, rind, and juice in a bowl; serve with pork and potatoes.