Heat enough oil in a pan for deep-frying the onion slices. Fry half of the sliced onions till golden-brown, drain on absorbent paper and keep aside.
Deep-fry the potatoes in the same oil till light brown, drain and keep aside.
Heat 4-5 tbsp oil in another deep pan; add the remaining onions and garlic paste. Saute on medium heat will the onions have turned translucent and light brown.
Add the tomatoes and sauté again till the oil clears and then add the cumin powder, chilli powder and turmeric powder. Add the chicken pieces and mix well. Cook on medium heat for 2 minutes.
Add 8 cups of water (2 cups of water for 1 cup of rice), season with salt and bring to boil.
Then add the potatoes, ginger strips, curd and cook for another 5 minutes.
Add the drained rice and cook on high flame for 5 minutes.
Lower the heat and cook for another 10 minutes or till most of the water has been absorbed.
Layer the top of the rice with the fried onions, kewra water and garam masala. Cook covered on low heat till the rice is completely done.
Mix just before serving. Best accompanied with raita/yoghurt dip, pickles and roasted pappad.