Ina's sticky ribs are easy to eat and just fall off the bone.
Heat the vegetable oil in a large saucepan over medium-low heat, and saute the onions and garlic for 5 to 7 minutes, until the onions are translucent but not browned. Add the chilli powder, ground cumin and red pepper flakes and continue cooking for 1 minute. Add the zest and ginger and cook for an additional minute. Add the vinegar, tomato puree, honey, mustard, soy sauce and orange juice and simmer uncovered on low heat for 15 minutes, until thick.
Marinate the ribs in 2/3 of the barbecue sauce for a few hours or overnight in the refrigerator.
Prepare a barbeque with a single layer of hot coals and then add a few more coals 5 minutes before cooking, which will keep the fire going longer. Place the ribs on the barbeque and cook for about 25 to 30 minutes, turning once or twice to cook evenly on both sides. Brush with the marinade as needed.