1.Preheat the oven to 165ºC. Arrange the ribs in a deep roasting tray. Combine water and half the jar of char siu sauce. Pour over the ribs and cover with foil. Cook for 1½ hours, checking once to turn the ribs.
2.Combine remaining char siu sauce, sweet chilli, ginger, garlic, sesame seeds, five spice, soy sauce and orange zest and juice.
3.Increase oven temperature to 185ºC. Drain ribs, reserving half a cup of liquid, and arrange in a single layer on lined shallow roasting trays.
4.Whisk the ribs’ stock into the sauce mixture and brush generously over each rib. Cook for 20-30 minutes, adding extra sauce once or twice until glazed and sticky.