Put the salt and sugar into a 500ml clean glass jar then slowly pour in the hot water. It is important to do this very slowly otherwise the glass may shatter from the heat.
Pour in the apple cider vinegar, put the lid on the jar and shake until the salt and the sugar are dissolved. Be careful not to burn yourself, as the jar will be hot. Use a tea towel to hold the jar if necessary.
Add the carrots to the hot pickle juice, put the lid back on the jar and leave to cool.
Once the pickles have cooled, you can eat them immediately or, better still, keep them in the fridge for at least 24h.