Put olive oil into a frying pan, finely chop the onion and one clove of garlic and sauté for 3 - 4 minutes until translucent.
In the meantime, peel the carrot, wash the celery and clean the mushrooms and cut everything into small pieces.
Add the carrot, celery and mushrooms to the frying pan that contains onion and garlic, stir and fry briefly. Wash the lentils from your jar and add to the vegetables. Stir and sauté for another 2 minutes over medium heat.
Add the tomato sauce from your jar and simmer at a low temperature with the lid on for about 25 minutes until they are cooked. Add splashes of water for the lentils to absorb and if the sauce gets too thick.
Fill a large saucepan with water and boil. Add salt and cook the pasta from your jar for about 8 minutes (al dente) and try occasionally until you like it.
Before serving sprinkle with nutritional yeast if desired.