For the marinade: Combine all ingredients for the marinade and coat spareribs with it. Divide bacon into 4 pieces, peel onion and cut into 0.5 cm thick slices (approximately 1/5 inch), making sure to keep rings intact.
Place ribs into a greased casserole pan and roast in preheated oven at 120°C (approximately 250°F) for about 2-2.5 hours. After one hour of roasting, add onions and bacon to the pan.
Baste spareribs with marinade often. Cut ribs into serving portions and arrange together with bacon and onions on a cutting board and serve immediately.