1.Preheat oven to 400 degrees. Season lamb generously with salt and pepper. Heat a large ovenproof skillet over medium-high heat. Add 2 tablespoons oil; heat until hot but not smoking. Add lamb; cook, turning once, until browned, 2 to 3 minutes per side. Pour off fat. Transfer skillet to oven; cook lamb until an instant-read thermometer inserted into thickest part of meat registers 130 degrees (for medium-rare), 20 to 25 minutes. Let lamb rest 10 minutes.

2.Meanwhile, make gremolata: Remove zest from orange using a vegetable peeler; finely chop zest (you should have 1/4 cup). Stir together zest, 1/3 cup orange juice (from zested orange), the lemon juice, parsley, and remaining 1/4 cup plus 2 tablespoons oil. Season with salt and pepper. Cut lamb into chops. Serve with the gremolata.