Put the lentils in a bowl; cover with cold water and set aside. Heat the oil in a large casserole or saucepan over a medium-high heat and add the onion, ginger and garlic with a pinch of salt. Fry for 8 minutes until turning golden. Stir in the curry powder, curry leaves, tomatoes and a good grinding of black pepper; cook for 2 minutes.
Drain the lentils and add to the pan, along with the stock and 250ml cold water. Bring to the boil, then turn down to a simmer and cook for 20 minutes until the lentils are soft. Stir in the chicken or turkey and the spinach, cover and cook for another 3-4 minutes, until the spinach is wilted.
Meanwhile, prepare the rice according to pack instructions. Check the seasoning of the curry, adding more salt, pepper and a squeeze of lemon juice to taste. Serve with the rice.
This curry offers a great way to use up leftover roast chicken or Christmas turkey. If you’d rather make the dish vegetarian, use chunks of roasted squash or lightly fried cubes of paneer instead.