Top and tail the leeks, carrots and celery.
Dice the carrots and celery in to cubes.
Slice the leeks in to 1cm rounds.
De-seed and finely chop the chilli.
Pick the sage leaves off the stalks and roughly chop.
Heat some olive oil in a large pan over medium heat. Add the leeks, carrots, celery, sage and chilli.
Hold the end of the thyme stalks over the pan and using two fingers, run them along the stalk and pull off the thyme leaves into the pan.
Add some salt and pepper and cook for 10 minutes until the vegetables have softened.
Drain and rinse the lentils and add to the pan with the vegetable stock cube and 50ml of water.
Cook for 5 minutes.
Stir through the oat fraiche and heat until hot.
Season more if desired and serve with a few sage leaves on the top.