Place the lentils in a bowl of cold water and leave to soak while you start making your daal. Peel and finely chop the onion. Peel and grate the ginger and garlic. Heat a large pan for 2 mins then drizzle in 1 tbsp oil. Add the onions with a pinch of salt and cook on a gentle heat for 10 mins to soften them and lightly caramelise the edges. Take care not to let them burn.
While the onions cook, coarsely grate the courgettes. Zest the lemon and cut it into quarters. Thinly slice the spring onion. Set to one side.
Drain and rinse the lentils. Add the ginger, garlic, daal spices and 1 tbsp mustard seeds to the pan with the onions. Cook for 2 mins, scraping the bottom of the pan so the aromatics don’t burn. Tip in the lentils and stir. Pour in 500ml boiling water and crumble in the stock cube. Cover and simmer for 10 mins, stirring occasionally.
Meanwhile, make your flatbreads. Tip the flour into a large bowl, saving 1 tbsp for later. Add a good pinch of salt. Drizzle in 1 tbsp olive oil and spoon in 2 tbsp yogurt. Add 2 tbsp cold water and mix together to form a smooth dough. Cover with a tea towel and leave to rest.
When the lentils have cooked for 10 mins, add in the courgettes. Pour in 200ml boiling water. Pop the lid back on and cook for a further 10 mins.
Divide the dough into 2 balls. Dust your worktop with the 1 tbsp of reserved flour and roll the balls as thinly as possible. They should be the size of a dinner plate. Rub each side with 1 tsp olive oil.
Squeeze in the juice from 2 lemon quarters. Taste and season the lentils. Turn off the heat and pop the lid back on.
Heat a large frying pan for a couple of mins. When hot, carefully lay one flatbread in the pan. Cook for 2 mins then flip over and cook for 2 mins on the other side. Remove it from the pan and cover with a tea towel to keep warm. Repeat with the remaining flatbread.
Spoon the daal into a couple of warm bowls. Top with 1 tbsp yogurt each. Scatter over the sliced spring onion and lemon zest. Serve with the warm flatbreads and a wedge of lemon each.