Potatoes, kohlrabi and onion and peel and dice. Fry the bacon in a pan until crispy, then remove it and set aside.
Add a little butter to the fat and sauté potatoes, kohlrabi and onions in it. Deglaze with the stock and milk, bring to the boil and cook for about 20 minutes. Puree the soup in the mixer or with the hand blender until smooth. Melt half of the cheddar in the soup while stirring over low heat, season to taste. Serve sprinkled with the remaining cheese and diced bacon.
Note: Since the potatoes contain and bind differently in starch, an exact amount of liquid cannot be given.