Heat your oven to 200ºC/Fan 180ºC/Gas 6. Peel half the swede, the carrots and parsnip. Chop the carrot and parsnip into bite-sized pieces. Dice the swede. Tip into a roasting tin. Drizzle with 1 tbsp oil. Season. Roast for 40-50 mins till tender and lightly charred.
Rinse and trim the leek. Slice into rounds. Rinse the lentils under cold water. Peel the ginger and turmeric (see tip). Grate them both. Warm 1 tbsp olive oil in a large pan. Stir and fry the leek, ginger and turmeric together for 5 mins over a medium heat.
Fill the kettle and boil it. Add 2 tsp of the chickpea spice mix to the pan with the leeks. Stir for 1 min. Add the lentils, coconut milk and 200ml hot water from the kettle. Bring to a simmer. Cover. Cook for 25-30 mins till thickened, stirring occasionally.
Tip the rice into a small pan. Pour in 300ml hot kettle water. Add a pinch of salt. Cover and bring to the boil. Turn the heat down. Simmer for 20-25 mins till all the water has absorbed. Take off heat. Steam, lid on, for 2-4 mins till the rice is cooked.
Rinse the watercress. Pop it into a salad spinner or pat dry with kitchen paper. Pick out any really large stalks.
When the lentils are cooked, stir in the watercress to wilt it. Taste and add salt and pepper if you think it needs it.
Divide the rice between 2 bowls. Fluff it up with a fork. Top with the lentil curry and the roasted roots.