Heat oil in a large pan and cook the onion and garlic over a medium heat for 3-4 mins until softened. Tip in the potatoes, carrots and parsnips. Turn up the heat and cook for 6-7 mins, stirring, until the vegetables are golden.
2-Stir in the curry paste or powder and stock, then bring to the boil. Reduce the heat, add the lentils, cover and simmer for 15-20 mins until thickened.
3-Season the casserole, then stir in most of the coriander. Heat through for another minute. Serve sprinkled with coriander, with a spoonful of yogurt and naan bread.