Have the lentils and the vegetables well washed (in cold water) and prepared as indicated in the ingredients description.
Heat the olive oil in a large saucepan. Add the onion and a pinch of salt and cook over a low heat, stirring frequently, for about 2 minutes. Add the potatoes and stir-fry for 2 more minutes until only lightly golden.
Add then the strained red lentils and stir. Cover with the vegetable stock (or with cold water otherwise) and leave to cook, covered with a lid, at a medium-low heat for approximately 20 minutes stirring from time to time. Add a teaspoon sea salt (or salt to taste) and stir.
Remove from the heat and with the help of a hand mixer (ideally a powerful one of at least 450 watt) mix it all well until perfectly combined.
Serve hot and optionally garnish each serving with fresh chives.
Recipe by Tasty Mediterraneo at https://www.tastymediterraneo.com/red-lentils-soup/