For the dal, heat the oil in a large saucepan over a medium heat. Once hot, add the cumin seeds and chilli flakes and fry for 20 seconds, or until the seeds start to pop.
Add the onion and cook for 2 to 3 minutes, or until just softened. Add the garlic, ginger, ground cumin, coriander, turmeric and salt and cook for 1 minute.
Then add the lentils, tomatoes, stock cube or pot and cold water and bring to the boil. Reduce the heat and simmer for 15 minutes.
Optional - before switching the heat off, add a handful of spinach and stir until wilted.
Meanwhile, make the naan breads - put the flour, salt and sesame seeds into a large bowl and mix well. Make a well in the centre and add the yogurt and cold water. Mix together to form a soft dough.
Put the dough onto a lightly floured work surface and knead for 1 to 2 minutes, or until it forms into a smooth dough. Divide it into 6 pieces and roll each piece into a ball. Flatten each ball gently using the palm of your hand, then roll them out to 5mm thick circles.
Put the oven on at a low setting. Heat 1 tsp of the oil in a large frying pan over a medium to high heat. Add 2 of the naan circles and cook them for 1 to 2 minutes on each side, or until golden brown and puffed up. Repeat with the remaining naans, keeping the cooked naans warm in the oven.
Add the coriander to the dal and stir. Serve with the naan bread and some mango chutney – yum, it's really delicious!