GET AHEAD Prick the aubergine, then lightly blacken it directly over a flame on the hob or in a hot griddle pan, turning with tongs. Remove to a board.
Halve the chilli lengthways and deseed, peel and finely slice the garlic, then peel and finely chop the onion. Crush the cardamom pods in a pestle and mortar and remove the outer shells, then pound up the seeds. Place a large non-stick ovenproof frying pan on a medium-low heat with 1 tablespoon of olive oil and the cumin, mustard and cardamom seeds. Strip in the rosemary and let it gently sizzle for a few minutes, infusing the oil and allowing the flavours to mingle. Add the chilli, garlic and onion and cook for 5 minutes, or until softened, stirring regularly. Chop the aubergine into 3cm chunks and stir into the pan, then add 1 tablespoon of red wine vinegar. Let it sizzle for a couple of minutes, then pour in the beans, juice and all, the lentils and 600ml of water. Set fire to the cinnamon stick, then sit it in the centre of the pan. Cover the daal and leave to thicken on a medium-low heat for 1 hour, loosening with splashes of water, if needed, and stirring occasionally. Season to perfection, tasting and tweaking, then cool, cover the pan and refrigerate overnight.
TO SERVE Preheat the oven to 150°C/300°F/gas 2. Place the covered pan of daal into the oven until hot through – about 1 hour. Stir well, and serve.