Cut off the rind and excess fat around the pork chops. Mix the chili powder, paprika, and some salt and pepper with the olive oil in a wide baking dish. Add the thyme, garlic, star anise, and coriander seeds. Add the pork chops and turn to coat. Cover and let marinate for at least 30 minutes, or in the refrigerator overnight.

Heat the oven to 350F. Bake the pork chops, uncovered, for about 15 minutes until the meat is just firm when lightly pressed.

Meanwhile, bring a pan of salted water to a boil. Peel the sweet potatoes and cut into 5/8- inch slices. Add to the pan and cook for 7 to 8 minutes until almost tender when pierced with a skewer. (They should be slightly undercooked at this stage.) Drain and refresh under cold running water. Dice the potatoes; set aside.

When cooked, transfer the chops to a warm plate, cover with foil, and rest in a warm place for 10 minutes. Squeeze out the soft garlic from the skins and return to the baking dish. Add the chile, tip in the sweet potatoes, and toss to mix. Season lightly and bake for 10 minutes, stirring once or twice, until the potatoes are tender.

Stir the coriander through the sweet potatoes and spoon onto warm plates. Add a pork chop to each plate and serve.