Preheat oven to 450°F.
Combine potato slices and 1 tablespoon oil on a rimmed baking sheet lined with parchment paper. Bake at 450°F for 10 minutes or until tender.
Heat 1 tablespoon oil in a skillet over medium-high. Top pork slices with 1/4 teaspoon salt and pepper. Add to pan; cook 5 minutes on one side. Remove from pan; add cider, and cook 1 minute. Stir in mustards. Remove pan from heat; stir in butter. Add pork to pan; let stand 3 minutes.
Combine potatoes, remaining 2 tablespoons oil, remaining 1/4 teaspoon salt, apple, fennel bulb, and remaining ingredients in a bowl. Serve slaw with pork and pan sauce. Garnish with fennel fronds.