2 tablespoons vegetable oil
1 (2-pound) boneless center cut pork loin, trimmed and tied
Kosher salt and freshly ground black pepper
1 medium onion, thickly sliced
2 carrots, thickly sliced
2 stalks celery, thickly, sliced
3 cloves garlic, smashed
3 sprigs fresh thyme
3 sprigs fresh rosemary
4 tablespoons cold unsalted butter
2 apples, such as Cortland or Rome peeled, cored and cut into 8 slices
2 tablespoons apple cider vinegar
1 cup apple cider
2 tablespoons whole grain mustard