Put the lentils, chickpeas, carrot & tomato pieces, salt, ginger and turmeric in a pan, then pour over the water.
Bring to the boil and remove the foam. Turn down the heat and gently simmer for 20-25 minutes, or until the dhal is cooked and it's almost creamy. If it’s too thick add more water.
Heat the oil in a frying pan and stir-fry the onion until softened. Stir in the cumin and mustard seeds for a minute, or until they start popping. Add the garlic and chilli and fry for another minute or so, stirring.
Add the curry leaves, stir for a few seconds, then turn off the heat. Add the asafoetida and garam masala powder, stir for a few seconds.
When the dhal is cooked, add the spinach and the spiced onion mixture, then turn off the heat. Cover and rest for a couple of minutes or until the spinach has wilted.
Stir the dhal, until well combined.
Serve with a squeeze of lemon juice and garnish with coriander leaves.