How to make fermented hot sauce

Why fermenting improves it

A vinegar hot sauce gets its acid from a bottle: sharp, one-dimensional and immediate. A fermented sauce makes its own lactic acid slowly, and along the way the bacteria produce a range of other compounds that give depth and a savoury quality.

Fermentation also softens the raw, green, vegetal edge of fresh chillies and develops fruitiness. The same chillies taste noticeably different after a fortnight in brine.

This is the process behind sriracha, behind Tabasco's long barrel ageing, and behind most of the hot sauces people describe as complex rather than merely hot.

The method

A fortnight of waiting, then ten minutes of blending. FoodHQ does not publish salt percentages, pH figures or keeping times for home fermenting. Those are safety numbers, they are set by a food safety authority rather than by a cookery writer, and the right ones depend on what you are fermenting and where you are. In the UK the Food Standards Agency is the authority — use a recipe from it or from another body with the same standing, and treat this page as the explanation of why that recipe is shaped the way it is.

1. Stem the chillies and roughly chop them. Wear gloves — this is the point at which people regret not doing so.
2. Add garlic, and any other vegetables you want: red pepper for body and sweetness, carrot, onion, a little fruit.
3. Pack into a jar and cover with brine made to a strength taken from a reliable recipe. Everything must sit below the liquid.
4. Weight it down. Chillies float, and anything above the brine will mould.
5. Cover so gas can escape and leave it somewhere cool and dark. It should start bubbling within a few days.
6. Leave it for one to four weeks, tasting occasionally with a clean spoon. It is ready when it tastes pleasantly sour as well as hot.
7. Blend the solids with some of the brine until smooth, then adjust with vinegar, salt and a little sugar. Strain if you want a smooth sauce, or leave it rough.

Finishing and variations

• Add vinegar at the end. It sharpens the sauce and, in a bottled sauce, matters for keeping — how much is a Food Standards Agency question.
• Strain it through a sieve for a smooth, pourable sauce, or leave it chunky.
• A little sugar rounds it off and is standard in sriracha-style sauces.
• Roast some of the chillies first for a smokier, deeper sauce.
• Add fruit — mango, pineapple, peach — for a Caribbean-style sauce.
• Carrot and onion give body and sweetness and are what many commercial sauces use to bulk out the chilli.
• Keep the leftover brine. It is sour and hot and excellent in a dressing or a marinade.

What to watch for

Floating

Chillies float and must be weighted below the brine. This is the commonest cause of mould in a chilli ferment.

Bubbling

Should start within two to four days. No activity at all after a week suggests it is too cold or too salty.

Kahm yeast

A flat white film. Harmless, skim it off.

Mould

Fuzzy and coloured. Discard the batch.

Colour

Red chillies stay red; green ones go olive. Both are normal.

Gloves

Genuinely necessary. Capsaicin on the hands transfers to eyes for hours afterwards.

Common questions