Set the oven broiler to high or heat a dry comal or cast-iron pan over medium-high heat. Broil or dry-roast the tomatillos, poblano peppers, serranos, onion wedges, and unpeeled garlic until blistered and well colored. The tomatillos should soften and collapse slightly, the poblanos should blacken in patches, the onion should take dark roasted spots, and the garlic should soften in its skins. This usually takes 10–15 minutes under the broiler or a little longer on the stovetop. Turn everything as needed for even roasting. Transfer the poblanos to a bowl and cover for 5 minutes to steam, then peel away most of the loose charred skin. Remove the seeds only if you want a slightly milder sauce. Peel the garlic cloves. The vegetables should smell sweet and roasted, not raw. The tomatillos must be fully softened, and the poblanos should be tender enough to blend smoothly. Steaming the poblanos covered for those few minutes after roasting loosens their charred skin considerably more effectively than trying to peel it away immediately off the heat — the trapped steam softens the skin's grip on the flesh beneath it.

While the vegetables roast, place a large dry skillet over medium heat. Add the pumpkin seeds and toast, stirring often, until fragrant, lightly golden in spots, and just beginning to pop, 3–5 minutes. Remove immediately so they do not darken too much or turn bitter. Toast the sesame seeds for 30–60 seconds until lightly golden and aromatic. Remove. Toast the torn tortillas in the same pan until dry, lightly blistered, and crisp in spots. If using the bread, toast it as well until dry and lightly golden. The pepitas should taste nutty and rich, not raw. The tortillas and bread should feel dry and firm so they blend in as a proper thickener rather than turning gummy. Pulling the pumpkin seeds the instant they begin popping, rather than continuing past that point for more colour, protects them from tipping into the bitterness that overtoasted seeds develop quickly once they cross from golden into truly browned.

Bring about 500ml of the chicken stock to a very gentle simmer in a saucepan. Add the chopped lettuce and cook for 30–45 seconds, just until wilted. Add the cilantro, parsley, epazote, and hoja santa if using, and wilt them for only 10–15 seconds more. Immediately remove from the heat. This step softens the greens, takes away the raw grassy edge, and helps preserve a vivid green color without overcooking the herbs. The greens should be wilted and bright green, not olive or dull. Do not simmer them for long. This is genuinely the single most colour-critical step in the entire recipe — chlorophyll, the pigment responsible for green colour in herbs and lettuce, degrades quickly under sustained heat, and the brief, staged wilting specified here — lettuce first, more delicate herbs added only afterward for an even shorter time — is calibrated specifically to soften everything just enough while minimising that colour loss.

In a blender, combine the roasted tomatillos, poblanos, serranos, onion, peeled roasted garlic, wilted lettuce and herbs with their cooking liquid, toasted pumpkin seeds, sesame seeds, toasted tortilla pieces, toasted bread if using, salt, black pepper, cumin, cloves if using, and oregano if using. Add another 250–350ml warm stock and blend until very smooth. The sauce should be thick but fully moving in the blender. Add a little more stock if needed, but do not over-thin it yet. For a more rustic traditional finish, stop once the sauce is very smooth but still has a faint natural texture from the seeds. For an extra polished finish, you can pass it through a medium sieve, but it is not necessary. The blended mole should be vividly green, creamy-looking, and thick enough to mound slightly on a spoon. It should not look watery or separated. Including the herbs' own wilting liquid directly in the blend, rather than discarding it, carries some of the water-soluble flavour and colour that leached out during that brief wilt back into the finished sauce rather than losing it.

Heat the lard or oil in a heavy saucepan or Dutch oven over medium heat. Carefully pour in the blended mole base. Stir immediately. It may sputter at first. Reduce the heat slightly and cook, stirring frequently, for 8–10 minutes. This frying stage is essential. It deepens the flavor, removes any raw blended taste, and develops the glossy body that makes the sauce feel complete. The mole will darken slightly from bright green to a deeper vivid green, become glossier, and thicken. The raw tomatillo aroma should mellow into a more rounded, savory smell. Even at this stage, where genuine transformation and cooking is meant to happen, the heat is kept moderate rather than aggressive — a harder fry would risk pushing the sauce's colour past that intended deeper vivid green and toward the duller olive tone this recipe is specifically built to avoid.

Slowly whisk in enough of the remaining warm chicken stock to bring the sauce to a thick, spoonable consistency. For a finishing sauce, it should be thick enough to hold soft swirls. For coating chicken or pork, it can be loosened a little more. Bring the sauce to a very gentle simmer and cook for 10–12 minutes, stirring often so the bottom does not catch. Taste and adjust the seasoning. Add more salt if needed. If the tomatillos are especially tart, add 1 teaspoon sugar, taste again, and only add the second teaspoon if it truly needs it. If the mole becomes too thick, loosen it with 1–2 tablespoons hot stock or water at a time. If it seems too loose, simmer a few extra minutes until it coats the back of a spoon heavily. The finished mole should be thick, glossy, and velvety, with a slight natural seed texture. It should cling to a spoon and spread into smooth swirls without leaking liquid at the edges. The instruction to keep this simmer genuinely gentle, rather than a firmer boil, is a continuation of the same colour-protection principle running through the whole recipe — an aggressive simmer at this late stage could still dull the sauce's hard-won brightness even after every earlier step protected it successfully.

Taste one final time for salt and balance. The finished flavor should be savory, herbal, gently nutty, lightly spicy, and bright but not sharp. Serve warm with a few toasted pumpkin seeds scattered over the top. The sauce should look lush and glossy, with a vivid green color and no visible oil separation. Scattering the toasted pumpkin seed garnish only at the very end, rather than incorporating it earlier, preserves both their crunch and their own visual presence against the smooth sauce.