Combine the rice and dhal in a bowl and rinse repeatedly until the water becomes clear. Soak for 30 minutes. Drain.
Heat the oil in a frying pan and add the cumin. Fry until it starts to pop, then add the onion. Stir fry for around 4 minutes then add the tomato, ginger, chili, turmeric and vinegar. Stir fry until the tomato breaks up, around 5 minutes.
Add all the ingredients to the bowl of a rice cooker plus around 600 ml of water (enough to just cover the rice/dhal).
Cook for 10 minutes then leave to keep warm for a further 15 minutes without opening the lid.