Heat the oil in a large pot.
Add the onions and cook until softened.
Add the mustard seeds and cumin seeds and cook for another minute.
Add the garlic and cook until fragrant.
Add the tomatoes, salt, chilli powder, turmeric powder, and cumin and cook for a few minutes.
Add the lentils and chickpeas and cover with water. Bring to a boil, then reduce heat and simmer for 20-25 minutes, or until the lentils are tender.
Stir in the spinach and cook until wilted.
Stir in the coconut yoghurt/cream and lemon juice.
For the dressing, combine the coriander, olive oil, and lemon juice.
Serve the soup with a drizzle of the dressing.