Blend the tomatoes and their juice, grated coconut, 1 tablespoon of the lemon juice, mustard seeds, and sugar in a hand blender or with a hand blender until smooth.
Heat the ghee in a large heavy saucepan and sauté the onions over low heat, stirring occasionally, until golden, 10 min. Add the coriander, curry leaves, cardamom, cumin, turmeric and ginger paste and sauté for 1-2 min, stirring throughout, until the spices begin to become fragrant.
Add pureed tomatoes and lentils and bring to a boil. Reduce temperature and gently simmer, covered, for 10 min.
3. pour in sweet potatoes, potatoes and carrots and simmer covered for another 15 min on low heat. Add zucchini, melanzani and remaining juice of one lemon, season with salt and simmer covered on low heat for 10-15 min until vegetables are cooked. Serve garnished with curry leaves.
Variation Any vegetable is suitable for this dish. Add varieties with longer cooking times to the saucepan first, add quick cooking ones 15 min later.
Tip: Stock up on high-quality spices – it pays off!