II
The Method
1
Place the pig's head sections, spine, heart, and lungs in a large pot. Cover with cold water generously, add a generous pinch of salt, and bring to a vigorous boil. Boil for 15 minutes, skimming constantly. Drain and rinse all pieces under cold running water. The water should run clear and the surface of the meat should be clean of grey foam.
2
Return the head, spine, heart, and lungs to the pot with fresh cold water to cover. Bring to a simmer and cook, partially covered, for 1 hour until the meat is approaching tenderness but not falling apart. Add the liver in the final 15 minutes of this cook — it requires less time. Reserve all the cooking liquid; this is the liquid for the recado. Remove the meats and set aside to cool slightly before stripping the head meat from the bone and cutting all offal into bite-sized pieces.
3
Char the chiles directly over a gas flame or on a dry comal, turning with tongs, until blackened on the outside — not merely toasted. Char the tomatoes, tomatillos, garlic, and onion on the comal until their surfaces are heavily blistered and dark. This char is the foundation of the recado negro's depth; insufficient blackening produces a flat, one-dimensional sauce.
4
Transfer all charred ingredients to a blender with the dissolved achiote paste, the dried shrimp, and 500 ml of the reserved pork cooking liquid. Blend to a smooth, dark, even purée. The sauce should be deep mahogany-black in colour with no visible chile skin or seed fragments.
5
Pass the recado through a medium sieve into a wide, heavy pot or clay pot. Bring to a simmer over medium heat, stirring frequently, and cook for 10 minutes until it darkens slightly further and loses its raw edge. Add the remaining pork cooking liquid as needed to achieve a loose, saucy consistency — it should coat a spoon but pour freely, not sit like a paste.
6
Add all the reserved meats and offal to the recado. Stir thoroughly to combine — the name revolcado reflects this full integration of cuts. Simmer, uncovered, over low heat for 1 to 2 hours, stirring occasionally and adding cooking liquid if the sauce tightens. The dish is ready when the sauce is deeply savoury and the gelatin released from the head and spine has given it a glossy, unified body.
7
Adjust salt. Serve directly from the pot into deep bowls or plates, accompanied by warm corn tortillas. The stew should be saucy enough to scoop with a torn tortilla.