Oaxaca, Mexico — specifically this charring technique is what defines the Central Valley and Sierra Norte mole negro tradition
The defining technique of mole negro is the deliberate charring of dried chiles (chilhuacle negro, mulato) and a piece of corn tortilla or dried bread until completely black. This blackening — often described as burning — provides the bitter, complex dark notes that make mole negro distinct from all other moles. The charred tortilla (or stale bread) acts simultaneously as a thickener and as a colour and flavour contributor. This technique is counterintuitive: it looks like a mistake but is essential.
Dark, bitter-complex, earthy — the char contributes a coffee-and-dark-chocolate note without actual coffee or chocolate being present
{"Chiles must be charred — not just toasted, but blackened on one side — in dry comal or dry pan","Tortilla or stale bread must also be charred to black — same dry pan, same technique","The charred elements are soaked in hot water, then blended with the other mole ingredients","Charring controls: a little char produces dark complexity; too much produces overwhelming bitterness","This technique is what differentiates mole negro from mole coloradito — the char"}
{"Do this step with kitchen ventilation — the charring of chiles produces acrid smoke","Practice: start with one chile, char to the correct level, taste the blended result — calibrate from there","The soaking water from charred chiles should be discarded — it is very bitter and can overwhelm the mole","Chilhuacle negro is the most important charring chile — ancho and mulato contribute, but negro carries the technique"}
{"Being too cautious with the charring — under-charred chiles produce brown mole, not negro","Charring in oil — the dry char technique is different from frying","Over-charring the tortilla — one piece should be very dark but not ash; ash is too much","Skipping the charring entirely and using dark chocolate as the black agent — completely different result"}
Oaxacan Home Cooking — Bricia Lopez; Mexico from the Inside Out — Enrique Olvera