Peel and chop the onion. We wash the leek well (only the white part) ensuring that there are no remains of land and we chop. Heat the oil in a saucepan and poach the onion and leek over medium heat for 10 minutes.
Add the lentils, the paprika, the vegetable broth and a pinch of salt. We cook to low heat for 15 minutes. We grind and, if we want it to be finer, we go through a Chinese or strainer. We adjust the salt if necessary and serve.