Kosher salt & freshly ground black pepper, to taste
In a large pot, add the (1.5 liter) bottle of Coca-Cola, onion, garlic, bay leaves and peppercorns. Add the ribs and, if necessary a bit of water just to ensure the ribs are submerged completely. Bring to a boil and reduce heat to a simmer, turning the ribs occasionally, until the meat pulls away from the bone, about 1 hour.
Meanwhile, to make the sauce combine the butter, onion, garlic, ketchup, mustard, brown sugar, Worcestershire sauce, and (12 ounces) Coca-Cola in large heavy sauce pan. Bring to a boil and reduce heat. Simmer for about 25 minutes stirring often until sauce is thickened and reduced. Season to taste with salt and pepper and let cool slightly. Using a blender, puree the sauce.
Preheat the grill to high.
Remove the ribs from the pot, pat dry, season with salt and pepper and brush liberally with the sauce. Grill, turning often, until charred on the outside, about 8 minutes. Loosely tent the ribs with foil and let rest for 5 minutes before cutting into individual ribs. Serve extra sauce on the side for dipping.