Peel and dice the potatoes and carrots and cook with the salt and 1 liter of water in a large saucepan until the potatoes and carrots are cooked through (approx. 15-20 minutes). Cook the red lentils with the vegetable stock in another saucepan for about 10 minutes.
Peel the onion and ginger and cut into small cubes, then in a pan
Simmer with the oil on a low flame and add the sugar, caramelize briefly.
Remove 1 cup of the potato water, you can add it back later as needed. Put the cooked lentils with the caramelized ginger and onion pieces in the large saucepan with the potatoes and carrots and puree everything. Season to taste with pepper and cream or coconut milk.
Add a handful of fresh coriander (with a stem) and tarragon (leaves only) to the hot soup
give, stir well and let steep for another 5 minutes.
Variants with shiitake mushrooms or non-vegetarian with shrimp or salsiccia or
Low-calorie with pumpkin instead of potatoes are imaginable.