Oven Barbecued Spareribs

This is very easy to prepare and will definitely be making this again.  Now I know the trick to keep the meat tender.
 
Ingredients:
1.36 kg pork spareribs (about 2 pcs)
2 tbsp + 2tsp butter
1 cup chopped onion
1 cup ketchup
6 tbsp chopped green bell pepper (capsicum)
2 tbsp chopped celery
4 tbsp lemon juice
2 tbsp + 2 tsp brown sugar (jaggery + demerara can be substituted)
2 tbsp + 2 tsp cider vinegar (or apple juice + white vinegar)
3 tsp worcestershire sauce
1 tsp salt
1 tsp prepared yellow mustard
1/2 tsp ground black pepper
1/2 tsp red chili powder

Procedure:
Saute onion in butter until translucent.  Add all the other ingredients except pork and bring to a boil.  Simmer uncovered for 10 minutes.  Cool down this sauce then use to marinate the spareribs for at least 3 hours.
Preheat the oven to 170°C for 10 minutes.  Place ribs in a shallow glass baking dish then cover with the marinade.  Cover the baking dish or pan with aluminum foil.  Bake for 2 to 3 hours in the oven at 170 °C.