Heat the oil in a saucepan, and add the onion and garlic. Cook over a medium heat for a few minutes, stirring occasionally, until the vegetables are fairly soft.
Meanwhile, add the broccoli to a food processor, and blitz until no large chunks remain.
When the onion is soft, add the processed broccoli and lentils to the pan, along with the stock and spices. Mix well, and bring to a simmer. Cook gently, stirring regularly, until the lentils are cooked and the mixture is at your desired consistency - around 20-25 minutes. Serve warm with rice or naan bread.