Bring 3 1/2 cups water to the boil. Add rice and salt; mix well. Bring back to the boil and reduce heat to medium. Cover and cook until the rice is tender and fluffy. Drain the excess water and keep the rice aside in a warm place.

Heat the oil in a deep pan; add onions and saute until golden brown. Remove the onions with a slotted spoon and drain on absorbent paper towels.

In the same oil, add black mustard seeds, curry leaves, and green chillies. Saute until the seeds pop. Add garam masala and stir. Add the cabbage leaves. Saute for 2 minutes. Add 1/4 cup water and salt to taste. Reduce heat, cover and cook until the water has evaporated. Remove from heat and keep aside.

To assemble, place the fried onions on the base of a large saucepan. Spread a layer of cooked rice and then the cabbage ending with the remaining rice. Cover the pan with a tight lid and cook on very low heat for 10 minutes. Mix carefully and serve.