Remove the stems of the chillies and loosely chop or blend. Slice the carrot, onion, and garlic.

Transfer all chopped ingredients to a 1 litre jar. Stir the salt into the water until dissolved, and then pour until all ingredients are submerged. Weigh down the chopped ingredients using a pickling weight or small ziplock bag partially filled with water. Remove any seeds or other ingredients that have floated free to the surface. I recommend capping with a lid that can take a twin bubble airlock. This will allow bubbles to escape as it all ferments, without allowing anything into the jar from the outside. Alternatively, regularly burp your jar by carefully cracking the lid open every few days. Store in a cool, dark place (heat will interfere with the ferment).

After 7 days, you should have a decent ferment. You can check for signs like bubbles, escaped liquid, and a cloudy brine. Successful fermentation creates an anaerobic environment, where only beneficial bacteria can survive; if you let oxygen in you may find unwanted bacteria have moved in (as well as missing out on vitamin-rich predigested carbohydrates, you could make yourself sick). So if no signs of fermentation are evident, you may want to discard and try again. Note that you can also ferment your sauce for another week or two if you prefer more complexity of flavour.

When you're ready to turn it into a sauce, drain out and retain the liquid. Thoroughly blend the chopped ingredients, add 50 ml of each vinegar, and slowly pour in the brine until it reaches a smooth consistency; this should take about 200 ml of liquid. Note you can vary the ratio of vinegars and brine to suit your taste. At this stage, add in any desired spices and herbs, or maple syrup if you'd like some sweetness to your sauce.

For a thin sauce, strain the mixture through a cheesecloth, otherwise transfer to bottles and jars, and refrigerate. The low temperature will slow the ferment, but you will still need to occasionally burp it (although using it regularly will have the same effect). It should keep for months, if you can make it last that long.

For a thick sauce as well as a thin sauce, blend the strained solids with the remaining 50 ml of each vinegar, and pour in the brine until it reaches your desired consistency. Bottle and refrigerate.