Wash and drain the split mung beans. Place in a heavy-based saucepan, pour in 800ml water and bring to the boil. Using a large metal spoon, skim off the froth that rises to the top. Stir in the turmeric. Cover, but not completely, with the lid, reduce the heat to low and simmer until tender, about 35 minutes. Add the salt and cook for a further 5 minutes, before removing from the heat.
Place the oil in a small frying pan and place over medium heat. Add the mustard and cumin seeds and cook until the mustard seeds begin to pop. Add the onion and curry leaves and cook until the onion is golden. Add the garlic and cook for 1 minute. Taste and add more salt if necessary.
Place the dal in a serving bowl and top with the onion mixture. Stir in before serving.
To make the cauliflower
Place the sliced cauliflower in a non-metallic bowl and sprinkle over a little flaky salt. Mix well, then cover and place in the fridge for an hour. Remove cauliflower from the fridge and drain away any juices that have collected. Add the remaining ingredients and mix well. Serve with the dal as a vegetarian meal or team with pan-fried fish.