Charring and fire-roasting
Also called fire-roasting, blistering, tatemado, blackening chillies
Quick answer
Roasting fresh chillies and aromatics over flame or on a hot dry surface until the skin blisters and blackens — for smoke, sweetness and peelable skins.
What it does to spices
Charring works on the surface and leaves the inside steamed. The skin of a chilli, tomato or onion blisters and blackens in the direct heat, developing roasted and smoky flavours, while the flesh beneath softens and sweetens in its own moisture; the loosened skin then peels away. A charred salsa and a raw one made from the same jalapeños and tomatoes are recognisably different sauces, and the blackened chillies of some Oaxacan moles are burned deliberately, to a degree that would ruin a dried chilli toasted on a comal.
Why it works
The surface dries and heats far above boiling, where sugars and amino acids brown and eventually pyrolyse, producing roasted and smoky aroma compounds and some bitterness; the interior stays near 100 °C in its own water and cooks by steaming. The capsaicinoids of a chilli lie in the flesh and placenta and are not reduced: a study of fresh Mexican peppers grilled at 210 °C measured more capsaicinoid afterwards than before. Charring changes a chilli’s flavour without reducing its heat.
How it goes wrong
- Charring dried chillies as though they were fresh: without water to protect them they burn through in seconds and turn acrid.
- Leaving too much blackened skin in a delicate salsa, where the bitterness dominates.
Spices it matters for
- Jalapeño — Charred for salsa asada.
- Poblano — Fire-roasted and peeled before stuffing.
- Chilhuacle — Blackened for the darkest Oaxacan moles.
- Onion
What it changes in the spice
The chemistry this technique sets off, explained in full on the science page.
What has been measured
Findings from studies and documented practice that concern this technique, each with the conditions it was made under and what it does not show.
Toasting and dry roasting · Increases Capsaicin
Poblano, Jalapeño, Serrano, Habanero
Grilling fresh Mexican peppers at 210 °C under household conditions raised their measured capsaicinoid content, by anything from 2.6 to 924.9 per cent depending on the pepper type, where boiling the same peppers had lowered it.
Conditions: in air · 210 °C · Household grilling as done in Mexican cooking
A charred fresh chilli is not made milder by the flame. Whether the rise reflects water driven out of the fruit, easier extraction from cooked tissue or both cannot be told from the published summary.
What this does not show: Read in the abstract only. The abstract does not say on what weight basis the contents were compared, and a grilled pepper has lost water, so the increase should not be read as capsaicinoid being made. The very wide range includes pepper types with almost none to begin with.
Measured on the spice
What it is called
The same technique in the traditions that use it, each named in its own terms.
Tatemado, asado
Mexican
Fresh chillies, tomatoes and onions roasted on a comal or over flame.
Where it is used
The pairings that specifically call for this technique.
- Jalapeño with tomato — Salsa in nearly all its forms. Jalapeño is grassy and green rather than merely hot, and tomato is sweet and acidic — the pairing works on flavour before it works on heat, which is why a salsa made with a hotter, blander chilli tastes worse rather than stronger.
Questions this page answers
- how to char chillies
- fire-roasting peppers
- what is tatemado