Simmer the lentils in the vegetable stock for half an hour.
Squeeze the lemons and save the peels.
Fry the onions and garlic in oil until translucent. Add the potatoes, celery, pumpkin and pepper and cook for a few minutes. Add the squeezed lemon juice and the vegetable mixture from the pan to the lentils and simmer everything together for another 10 minutes. Add the ground coriander and cumin and simmer for another 10 minutes.
Then take the soup off the stove. Add the herbs and finally season the soup with the lemon juice and salt as required.
Tips: If you want, you can add meatballs as an insert. You can also prepare the soup with zucchini or turnips.