Combine the lentils, water and tamarind water in a large pot and bring to a boil. Reduce heat, cover and simmer until lentils are soft and mushy (about 30 minutes). Check on the lentils a few times during cooking, and stir with a wooden spoon, to make sure they’re not sticking to the bottom of the pot and burning. You can always add a bit more water or vegetable stock if they look like they need it.
Heat oil in a medium or large fry pan over medium heat. Add onion and cook until starting to turn golden brown (about 6-8 minutes). Add a bit more oil, garlic, mustard seeds, ginger and spice mix. Cook a further 2-3 minutes until the mustard seeds start popping.
Stir onion mixture, crushed tomatoes, salt, carrot, cauliflower, beans and eggplant into the pot of lentils. Cover and simmer for 15-20 minutes until vegetables are tender. Mix in lemon juice at the end, taste and add more salt and/or pepper to taste.
Drizzle over coconut cream (if using), and garnish with fresh red chilli and coriander.