Preheat oven to 200F.
In small bowl mix together the garlic powder, thyme, paprika, sugar, salt, cayenne, black pepper and mustard.  Set aside.
If the ribs still have the membrane on the back, remove it.
Cut each rack into 3 pieces.
Lightly rub the ribs all over first with the vegetable oil then with the dry rub.
Arrange the ribs in a large baking dish, add water to dish until 1" deep (note - beer also works great!).  Cover dish with foil and place on the center rack.
Braise for 4 to 6 hours or until tender and the meat starts to pull back from the bone at the ends.
Paint the glaze on the surface of the ribs.
Finish the ribs on the BBQ until sticky and starting to caramelize.
Cut into individual ribs and serve.