Heat the oil in a frying pan over medium-high heat. Brown the pork chops, in batches, about 5 minutes per side. Transfer to an oven-proof casserole dish, arranged in a single layer.
In the same pan, add the onion and ginger; cook until softened, about 5 minutes. Pour in the orange juice and stock, reserving 2 tablespoons juice. Stir together the cornflour and reserved juice, then add to the pan. Bring to the boil, stirring continuously. Add the raisins, salt and pepper; pour the sauce over the pork chops.
Bake in the preheated oven, covered, until the pork is tender and cooked through, about 45 minutes. Remove the lid during the last 15 minutes of baking to brown the pork chops and thicken the sauce.