Place the dried chillies in a small pan and pour over enough vinegar to cover them. Bring to a simmer over a medium heat and simmer for 10 minutes. This step reduces the pH of the chillies and significantly reduces the risk of bacterial growth in the finished oil.
Remove the chillies from the vinegar using tongs or a slotted spoon and place on kitchen roll to drain. Allow to cool completely.
Place the cooled, drained chillies into a clean pan with the oil. Heat gently on a low heat until the oil just begins to simmer.
Simmer on a very low heat for 5 minutes. Do not allow the oil to boil hard or the chillies will burn and taste bitter.
Turn off the heat and allow the oil and chillies to cool completely in the pan — this allows further infusion as the oil cools.
Pour the cooled oil and chillies into a sterilised glass bottle with a pouring spout. Seal and store in a cool dark cupboard for up to 3 months.
