Heat a large saucepan and dry-fry 2 tsp cumin seeds and a pinch of chilli flakes for 1 min, or until they start to jump around the pan and release their aromas.
Scoop out about half with a spoon and set aside. Add 2 tbsp olive oil, 600g coarsely grated carrots, 140g split red lentils, 1l hot vegetable stock and 125ml milk to the pan and bring to the boil.
Simmer for 15 mins until the lentils have swollen and softened.
Season to taste and finish with a dollop of plain yogurt and a sprinkling of the reserved toasted spices. Serve with warmed naan breads.