In a large, heavy-based pan on a low heat, fry the onion, celery, carrot, bay leaf and a pinch of salt in the olive oil, until soft and fragrant.
Add the pumpkin/squash, sage and another small pinch of salt, then stir for a minute or two. Add 1.3 litres of water and the lentils, simmer gently for 10 minutes, then stir in the pearl barley.
Simmer for another 25 minutes, until the barley is swollen and soft and the pumpkin has collapsed into soup – if at any point the pan looks dry, add more water.
To serve, zigzag some more olive oil or flaxseed oil on top, and maybe some chopped red chilli and/or sage leaves fried until crisp and crumbled on top.