Heat your oven to 200°C/Fan 180°C/Gas 6. Tip the lentils into a bowl. Cover with cold water and leave to soak.
Halve the aubergines and slice lengthways into thick wedges. Place them in a roasting tin and brush with 1 tsp oil. Season and roast for 30 mins till tender and charred.
Peel and finely chop the onion. Peel and grate the garlic and ginger. Crumble the stock cube in a heatproof measuring jug. Pour in 500ml boiling water to dissolve.
Add the onion to a pan with a good splash of water. Season well. Cook over a medium heat for 5 mins till the onion is soft and glossy. Stir often while it cooks.
Stir in the garlic and ginger. Add the cinnamon stick, 4 cloves, the curry leaves and 1 tsp of the turmeric. Mix well.
Drain the lentils and add to the pan. Pour in the vegetable stock. Cover and bring to the boil. Turn the heat down and simmer for 20 mins, stirring now and then, till the lentils are thick.
Taste the daal and adjust the seasoning. Fish out any spices you can see, like the cinnamon stick or cloves. Stir in the spinach so it just wilts. Ladle the daal into warm bowls and top with the aubergine wedges. Serve straight away.