Kosher salt and freshly ground black pepper, to taste
1⁄2 cup Dijon mustard
10 tbsp. olive oil
3 tbsp. fresh lemon juice, plus more to taste
2 cups panko breadcrumbs
15 tbsp. unsalted butter
3 tbsp. minced sage
3 cloves garlic, peeled and smashed
8 slices swiss cheese
1⁄2 cup capers, rinsed
2 cups baby arugula
4 buns, toasted
Season pork with salt and pepper. Whisk mustard, 1⁄4 cup olive oil, and 2 tbsp. lemon juice in a bowl. Coat pork in mustard dressing, then pack with panko. Working in batches, heat 3 tbsp. butter and 2 tbsp. olive oil in a 12" skillet over medium-high; cook pork until golden, 2-3 minutes. Flip, then top with capers and Swiss cheese; add 2 tbsp. butter, sage, and garlic and cook until pork is cooked and cheese is melted, 2 minutes more. Divide 2 slices each pork between buns, then top with arugula. Serve immediately.