For the daal, add water, one tablespoon salt and ginger. Cook until it becomes tender. In a heavy based pan, heat butter and oil. Add cumin seeds and fenugreek leaves.
When they begin to splutter, add tomato puree, remaining salt, chilli powder and sugar. Stir-fry over high flame, till the oil separates. Add cooked dal and bring to boil. The consistency should be such that the daal should move around freely when stirred, otherwise add a little water. Leave to simmer, uncovered, till well blended. Stir-in cream and once it gets heated through, serve immediately, garnished with green chillies.