Soak corn husks in hot water for 30 minutes, weighting them with a plate. Rinse and drain. Meanwhile, remove tough stems from the chipilín, wash the leaves thoroughly, drain and chop coarsely.

Mix masa harina with 600 ml warm water and salt. Rest 10 minutes. Beat the softened lard for 3–4 minutes until lighter, then gradually beat in the hydrated masa. Fold in chipilín. The dough should be soft and spreadable; add water a tablespoon at a time if crumbly.

Divide the dough into 16 equal portions. Spread each portion in the center of a softened husk, leaving room at the edges and narrow end. Fold the long sides over the filling, then fold the narrow end upward. Do not wrap tightly enough to squeeze the dough out.

Add water to the steamer below the rack and bring it to a simmer. Line the rack with spare husks. Stand tamales folded-end down with the open ends upward, leaving spaces for steam. Cover with spare husks and the lid.

Steam over steady medium-low heat for 60–75 minutes, checking the water level and adding boiling water along the side when needed. Keep the water below the tamales and do not let the pot run dry.

Remove one tamal carefully and rest it for 5 minutes. It is done when the masa feels set rather than wet and pulls away from the husk. If still sticky and pasty, steam the batch 10–15 minutes longer and test again.

Turn off the heat and rest the tamales 10 minutes before serving. Remove the husks before eating. Refrigerate leftovers promptly and use within 3–4 days; reheat the center to 165°F (74°C).