Put the rice in a bowl and pour the plain yoghurt over it. Use just enough yoghurt to barely cover/submerge the rice. Cover the bowl and let this sit and soak for about 2 hours.
Pour the rice-yoghurt mixture into a processor and blend just a little bit to sort of break down the rice grains. It doesn't have to be smooth, you want to leave bits and pieces of rice coz this adds to the crunchiness of these bhajias. Turn the mixture back into the bowl.
Then, add the chopped onion, chopped coriander, methi/fenugreek, garlic paste, chopped chilli and salt. You can even add cumin powder if you want. Give it a taste and adjust if needed.
Now add the gram flour a little at a time and stir just until the consistency is such that you can pick a ball and easily form flat bhajias/fritters out of the mixture. Stop adding gram flour once you find you've reached that consistency.
While the oil is heating, shape the rice bhajias. Deep or shallow fry them on medium heat. Blot well to get rid of excess oil and serve with ketchup or chili sauce or chutney.