If you don't want your pickled chillies to be too spicy, you can rinse them in a colander with cold water to remove some of the seeds.
Place the chillies into a sterilised glass jar.
Mix the remaining ingredients in a small jug.
Pour the pickling liquid into the jar over the chillies.
Cover the jar and keep in the fridge.
Kitchen Notes
RED CHILLIES VS GREEN CHILLIES If you are using green chillies, they will lose their vivid green colour after 4-5 days. Red chillies will keep their bright red colour.
RECIPE CREDIT This recipe adapted from Rachel Khoo
STORAGE TIPS The pickled chillies keep well in the fridge for a few weeks but will lose a bit of their heat over time. I imagine that they would keep for longer, but I tend to make these in small quantities which we use within a few weeks.