Mash the boiled potato and carrot together until there are no lumps.
Add the rest of the ingredients to this mixture (except corn flour and oil).
Mix well with fingertips until it's a homogenous, damp mixture. The moisture from the potato and carrot should be enough to bring it together. Don't add any water.
Roll into small lime-sized balls.
Dust with corn flour. This is an optional step because I didn't find much difference in texture between these and the ones I didn't dust. Also, if you leave them plain, the oil stays clear and doesn't leave a white layer on the koftas.
Heat a pan and add enough oil to submerge the koftas half way. You can deep fry the koftas but it's really not necessary. You can also
use a paniyaram pan to do the frying
. Gently place the koftas in the hot oil.
Turn gently when golden brown on one side. Keep the fire medium low to ensure the inside is cooked too.
Drain on to paper towels and serve hot with ketchup or mint chutney.