For the carrot and potato soup, peel and dice the carrots and potatoes and finely chop the onion. Heat butter or canola oil in a pan and fry the onions in it.
Add the vegetable cubes and fry briefly.
Pour in soup or water, add a sprig of thyme and cook over low heat until tender.
Remove the thyme sprig and puree the carrot-pea soup with a blender.
Stir in sour cream or whipped cream and season with a little salt and pepper.