Bring 375ml / 13fl oz (1 1/2 cups) water to a boil in a large, heavy-based pan, add the dal, and cook for about 10 minutes.
Add the gourd, tomatoes, and chillies and cook for about 20 minutes, or until the gourd is soft and tender but not mushy.
Heat the oil in another pan over medium heat, add the garlic, ground spices, and season with salt, then stir-fry for about 1 minute. Add the vegetables and simmer for 5 minutes. Remove from the heat and allow to cool.
Heat the oil for the seasoning in a small frying pan (skillet) over medium heat. Add all the ingredients and fry for about 2 minutes, or until brown.
Pour over the vegetables and cover immediately. Garnish with coriander leaves and serve.