Start with the cold oil in a frying pan. Add the sliced garlic cloves and the chillies. Medium heat and stir from time to time to allow the oil to infuse with the garlic and chilli flavours. Once the slices of garlic are turning golden, add the peeled prawns. After just 30 seconds, remove the pan from the heat and cover it with a lid for 2 minutes. The prawns will be cooked by then.