Bring 2-3 litres of water to the boil in a large wide pot. Wash the ribs, dab dry and cut between the rib bones into pieces with 5-6 ribs. Add to boiling water. The meat should be completely covered with water.
Simmer for about 1 1⁄2 hours at low heat.
Meanwhile, for the BBQ sauce, peel onions, garlic and ginger and dice finely. Heat the butter in a pot. Fry the onions, garlic and ginger in it. Sprinkle with sugar and caramelise briefly while stirring.
Deglaze with vinegar, ketchup and Worcester sauce and bring to the boil. Boil down over medium heat for about 15 minutes until thick. Season to taste with salt, pepper and sugar.
Preheat oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer). Line baking tray with baking paper. Lift out the meat and place it on the baking tray. Brush the surface with half the BBQ sauce.
Bake in a hot oven for about 20 minutes. Spread with remaining BBQ sauce again and again. Fry for another 20 minutes.