Preheat the oven to 220°C fan / 475°F and line a roasting tray with baking paper.
Trim the ends off the aubergines, then slice them into bite-sized chunks. Add them to the roasting tray with the garam masala, a drizzle of oil and a pinch of salt. Mix, then roast in the oven for 30 minutes or until tender and charred around the edges, stirring halfway.
Rinse the lentils under cold water in a fine sieve, then add them to a large casserole pot or saucepan, followed by 1.5 litres (6.25 cups) of water. Quickly bring the lentils to a boil, then reduce to a gentle boil.
Skim as much scum as you can that rises to the surface, then stir in the cinnamon stick, turmeric and small pinch of salt. Now cook the lentils uncovered for 25-35 minutes or until they reach a soup-like consistency, stirring occasionally. If the dhal thickens too quickly, add another 1-2 cups of water and quickly bring back to a gentle boil. Note: depending on what pot you use and the level of heat, the dhal might take a little longer to thicken.
Meanwhile cook the rice as per the packet instructions, then remove from the heat and set aside with the lid on.
When the lentils are almost ready, start making your tarka. Add a generous drizzle of oil to a frying pan on a medium-high heat. When the oil is hot, add the cumin seeds, mustard seeds, garlic, ginger and chilli. Stir and cook for 2 minutes or until the spices are fragrant, but be careful not to burn them.
Remove the cinnamon stick from the lentils, then quickly - while the oil is hot - pour in the tarka, along with half of the roasted aubergine. Stir well, then season generously with more salt. Note: the key to this recipe is seasoning really well with salt, which will enhance all the aromatic flavours in the dhal.
To serve, add the rice to bowls, followed by the dhal. Top with the remaining aubergine, yoghurt and coriander leaves. Enjoy!