Cut the peeled onions into small cubes and sauté them lightly brown in a saucepan with butter over low heat. In the meantime, peel the carrots, chop them into thin slices and add to the brown onions. After 5 minutes, fill up with the warm water, add a pinch of salt and increase the heat.
Then peel the potatoes, cut them into small cubes and add them. When the soup boils, let it simmer over low heat (about 20 minutes) and add the spices. Can also be thickened with flour or starch as desired.