Spray a large saucepan with low calorie cooking spray, place over a medium heat and sauté the onions and peppers for 3-4 minutes, until they are beginning to soften.
Add the garlic and curry powder, and cook for another minute, allowing the spices to become fragrant.
Add the carrots, butternut squash and lentils to the pan, then stir in the stock, tomatoes and tomato puree.
Bring the soup to the boil, then reduce the heat and simmer for 10 minutes.
Add the rice and continue cooking for a further 20 minutes, until the vegetables are soft.
At this point, you can blend the soup if you wish, but we prefer it chunkier, so take a fork or a masher and lightly crush some of the butternut squash. This will thicken the soup, while keeping a chunkier texture.
Stir through the yogurt, lemon juice and coriander and serve in a warmed bowl.