This is something that I always have on hand in my pantry. I will make it by the litre and store it in large swing-top jars. I give it as gifts at Christmas, or favours at events. My mum will bribe her friends to babysit her cat with promises of it. It is one of those things that is just better when it's homemade, and once you have tried it, you will never settle for mediocre store-bought chilli oil again. The recipe is also very versatile - you can double the quantities or make half, as you wish. Do not use Italian chilli flakes for this recipe (the dark red circular-shaped flakes with seeds); it must be bright red crushed Asian chilli flakes, which are finely ground and have a distinctive colour and flavour. Korean chilli flakes (gochugaru) also work well.