To a large pot, add the ribs, bay leaves, the onion stuck with cloves, 2 teaspoons of salt, and enough water to cover by 1 inch. Bring to a boil, then turn the heat to medium-low and simmer, partially covered and skimming off any foam that rises to the surface, until the meat pulls easily from the bones, 1½–2 hours. Using tongs, transfer the ribs to a bowl and set aside to cool. Through a fine-mesh sieve set over a separate bowl, strain the broth, discarding the solids, and set aside.

When the ribs are cool enough to handle, pull the meat from the bones, discarding the bones and any excess fat. Slice or pull the meat into bite-size pieces and set aside. Wipe out the pot and return it to the stove.

Fill the pot halfway with water and bring to a boil. Add the tomatillos and cook until softened slightly, 3–4 minutes. Strain and transfer to a blender along with 1 cup of the reserved broth. (Wipe out the pot and return it to the stove.) Blend to a coarse purée, then transfer to a medium bowl.

In the empty blender, purée the lettuce, radish greens, cilantro, epazote, pumpkin seeds, sugar, black pepper, cumin, chiles, garlic, hoja santa, quartered onion, and 1 cup of the reserved broth, then add it to the tomatillo mixture. (The sauce should be thick and creamy but pourable; thin with broth as needed.)

To the empty pot, add the oil and turn the heat to medium. When it’s hot and shimmering, add the sauce (it will splatter) and simmer, stirring frequently, until thick and concentrated in flavor, 10–15 minutes. Season to taste with salt. (If the sauce looks too thick, add broth; reserve the remaining broth for another use.) Add the reserved pork and stir to coat. Serve hot with tortillas on the side. Garnish with the radishes, cilantro, and onion if desired.