Pre-heat the oven to 200 °C, setting it to fan function, and then reducing the heat to 180 °C for the baking.
Cut the garlic cloves and the onions into half. Cut in half the chili pepper, too, and remove its core. Slice the celery. You may want to cut the spare ribs in half as well.
Put all the ingredients – together with the sea salt – in a big pot and pour onto it as much water as what covers it all. Bring the water to a boil and then cook the meat at low heat under a lid, for about 40 minutes.
Finally, take out the ribs from the pot, remove the skin from the bony side and then place the ribs in a tin, dabbing them with the barbecue sauce. Bake them in the hot oven for 40-45 minutes. From time to time, dab the ribs with the barbecue sauce. When they are done, sprinkle them with rosemary.