First of all cut the kidney into pieces as desired, big or small and then keep them immersed in water with turmeric, vinegar and wheat flour added to it.
Add about 2 tablespoon of each and leave aside for 15 minutes.
In a pan, heat half of oil and add onions, ginger garlic paste, salt, coriander powder and the kidneys
Cover and cook with a cup of water added to it on a low to medium high heat.
They all get cooked nicely and what left is a lot of masala.
After 15 minutes, open the lid and add the rest of the oil along with the red chilli powder and fry it.
The masala consistency depends upon your choice. Fry it accordingly and switch off the flame after 5 minutes.
I usually dry up half of the masala by sauteeing and frying it and leave the other half as it is.
It tastes good even with just a steaming hot plate of simple boiled rice. Nothing else is needed.
Mix this masala along with the rice and enjoy it to the fullest.