Place the chops in a wide dish. Sprinkle over the oil, garlic, sage, fennel seeds and 2 tablespoons of the balsamic vinegar. Turn to coat evenly, then cover and place in the refrigerator to marinate for 1 hour.
Preheat the oven to 200 degrees C. Combine the onions, potatoes and parsnips in a large roasting tin. Add the pork chops with their marinade and turn the vegetables to coat evenly. Spread out the vegetables in a single layer, with the chops on top. Season to taste. Roast for about 40 minutes until the vegetables are tender and golden.
Core the pear and cut into eight slices. Toss in the remaining balsamic vinegar and the maple syrup. Remove the roasting tin from the oven and arrange the pear slices over the chops, spooning over the syrup mixture.
Return to the oven and roast for a further 10–12 minutes until the pears are tender. Serve the pork chops topped with the pear slices and juices, with the roasted vegetables alongside and, if you like, sage leaves scattered over the top.