Cut the spareribs into two or three rib portions. This is often made easier using kitchen shears.
Place the ribs in the bottom of a large pot, and cover them with cold water. Cover the pot and bring it to a boil (watch carefully or it will boil over). Reduce heat and simmer for 20 minutes.
Turn off the heat. Ribs can be left in the water for half an hour or you may proceed to the next step immediately.
Drain the ribs. Sprinkle with about 1 tablespoon of flour and place in large flat pan, one or at most two layers high.
Sauté the onion, celery, and sweet pepper until the onion is clear and soft.
Add the vegetables to the spareribs. Mix the lemon juice, vinegar, Worcestershire, brown sugar, water, and barbecue sauce together and pour the mixture over the ribs and vegetables. Cover the ribs with tin foil and bake in 350 (175C) oven for at least one hour (up to 1 1/2 hours).
Remove the ribs to a separate bowl. The sauce may be thickened with a tablespoon of cornstarch and a little bit of cold water. It may not be necessary, since the flour sprinkled on the hot boiled ribs will thicken the sauce naturally.
The sauce is served with the ribs and is great with mashed potatoes or rice.
