Preheat the oven to 180°C/350°F. In a small bowl, mix the paprika, salt, onion, garlic, crushed red pepper, cumin, coriander, black pepper and oregano; rub all over the ribs. Transfer the ribs to a large roasting pan and cover tightly with foil. Roast for 2 hours, until the ribs are very tender.
In a saucepan, whisk the honey, sherry, soy sauce, tomato paste, salt, Sriracha and bitters. Boil until reduced by half, 8 minutes.
Increase the oven temperature to 200°C/400°F. Uncover the ribs and transfer them to 2 large rimmed baking sheets. Let cool to room temperature. Cut the racks into individual ribs. Brush the ribs with the glaze and roast in the upper and lower thirds of the oven for 15 minutes, until richly lacquered; brush the ribs halfway through with the remaining glaze. Serve the ribs hot or warm.