To grill the peaches, heat a grill pan over high heat. Place the peach halves on a tray or in a bowl and toss with the oil and a pinch of salt and black pepper. Make sure the peaches are evenly coated in the oil. When the grill pan is hot put the peaches cut side down and grill for 5 to 7 minutes or until there are solid grill marks. Flip and cook for a further 4 to 5 minutes, until the other side has grill marks and the peaches are just beginning to soften.