Heat a glug of olive oil in a large saucepan over a medium-high heat then add the onion and fry until soft, about 3-4 minutes.
Add the carrots, celery and garlic, stir and fry for another 2-3 minutes.
Stir in the lentils, then add the mushrooms, dried herbs and tomato paste.
Pour over the stock, the full tin of tomatoes then fill the empty tomato tin with water and pour that in too.
Add the soy sauce then stir everything together well, season with salt and pepper and bring to the boil.
Simmer over a low heat for 40 minutes, stirring regularly.
Serve over your favourite pasta with a sprinkle of grated cheese.
Can be frozen for up to 2 months - allow to defrost and then reheat in a saucepan with a splash of hot water.