Choose glass jars with an airtight, metal lid and ensure they have been washed in the dishwasher or by hand in hot soapy water then rinsed well. Check that the metal lids do not have rubber inserts - if they do, allow them to air dry instead of placing in the oven. Preheat the oven to 270 F (130 C). Place the jars and lids on a baking tray. Heat in the oven for at least 20 minutes, then remove and allow to cool before filling.

To begin, carefully wash and thoroughly dry the chillies. Then, remove the stalks and finely slice the chillies, seeds included. Do not use any which have blemishes or bruises.

I recommend that you wear food-safe, disposable gloves when handling the chillies. Avoid touching your face or eyes as the active ingredient, capsaicin, can irritate the skin and cause burning. After cutting the chillies, discard your used gloves and carefully wash your cutting board and knife.

In a non-reactive glass or ceramic bowl, prepare a vinegar and salt brine. Combine the two ingredients and stir them well. Add the chillies along with their seeds. Ensure that they are covered with the brine, adding more if necessary, using a ratio of 1 tablespoon of salt for each cup of vinegar.

Stir the chillies then cover them with cling wrap and set them aside in their vinegar and salt bath for a minimum of 24 hours. Stir once or twice during this time. This process removes some of their moisture, increases acidity and assists with the preservation.

After that time, drain the chillies well in a fine sieve, discard the vinegar, pack the chillies into the sterilised jar and completely cover with olive oil. There will be some air pockets; wait until the oil has settled, you may need to add a little extra.

Store the chillies in a cool, dark place. The chillies will last for about 3 months, but are best consumed within the first 2 as they soften in texture the longer they sit in the oil. Alternatively, you may prefer to store them in the refrigerator. The olive oil will solidify and become cloudy but will become liquid again when the chillies return to room temperature. Always use clean utensils when removing the chillies from the oil.