Wash the cucumber. Cut off both ends and discard.
Use a peeler to carefully slice the cucumber lengthwise all the way down into long thin ribbons. You may also use the peeler to slice them thinly from the ends for shorter thin ribbons.
Next, chop or slice both the onion and the chillies. Combine them with the cucumber. Add the black pepper and salt too. You may also add the chilli flakes for extra flavours. Squeeze a few drops of lime and give it a good mix.
Viola, it is ready to be served. This side can be served with rice and curries, ghee rice, and also great for biriyani.