Peel and chop the onion and carrots into small pieces. Peel and finely chop the garlic. Rinse the red lentils in a sieve and strip the thyme leaves from their stalks.

Warm the olive oil in a large saucepan over a medium-low heat. Add the onion and carrots and cook for 5 minutes, stirring. Add the garlic and thyme and cook for another minute.

Add the rinsed lentils and 1.2 litres of tap water. Bring to the boil, then reduce the heat and simmer, stirring occasionally, for 20–25 minutes or as directed on the lentil pack, until the lentils and carrots are completely tender.

Add a little extra water if the soup becomes too thick. For a smoother soup, remove the pan from the heat and carefully blend with a stick blender; otherwise leave it chunky or mash lightly.

Stir in the salt and pepper, taste and adjust to suit, then serve hot.