How to Make It
Bring the water to a boil in a large heavy casserole. Season the spareribs with 2 teaspoons of salt. Add them to the casserole and cook over moderate heat, stirring occasionally, until the water has evaporated and the ribs have rendered some of their fat, about 30 minutes. Continue to cook the ribs, turning occasionally, until browned and crisp, 10 to 15 minutes longer.
Meanwhile, bring the stock to a boil in a medium saucepan over high heat. Remove from the heat. Heat a medium cast-iron skillet or griddle. Add the ancho chiles and cook over moderate heat, pressing lightly with a wooden spoon, until pliable and slightly blistered, about 30 seconds per side. Add the chiles to the hot stock and let stand until softened, at least 20 minutes.
Scatter the cloves in the same skillet and cook until fragrant, 15 to 20 seconds. Transfer to a plate to cool, then grind to a powder.
Scatter the garlic cloves in the skillet and cook over moderately low heat, turning, until softened throughout and browned in spots, about 15 minutes. Transfer the garlic to a plate and let cool slightly, then peel the cloves.
Transfer the ancho chiles and 2 cups of their broth to a blender. Add the ground cloves and the roasted garlic and puree until smooth.
Pour the ancho sauce and the remaining ancho broth over the ribs in the casserole and bring to a boil, scraping up any browned bits from the bottom of the pot. Cover partially and simmer over moderately low heat until the meat is tender and the sauce has reduced to 2 cups, about 45 minutes. Season with salt and spoon off some of the fat from the sauce. Transfer the ribs and sauce to a deep platter and serve.