Clean kohlrabi: Remove the stems and the leaves of the kohlrabi. Keep the leaves separated as they will be only added to the soup towards the end of the cooking process.
Chop: Place the kohlrabi bulb on a cutting board and slice off the top and bottom, removing the small woody part at the bottom of the kohlrabi bulb. Peel the skin with a knife or vegetable peeler like you would peel an apple. Discard the skin. Cut the kohlrabi bulb and the stems into cubes.
Chop vegetables: Peel and cube the potatoes as well. Finely chop the onion.
Saute vegetables: Heat the oil in a soup pan and cook the onion for about 2-3 minutes or until translucent. Add the cubed vegetables and cook for about another 4 minutes, stirring a few times in between.
Simmer: Add the vegetable or chicken stock, bring to a boil, turn down the heat and simmer the kohlrabi soup for about 20 minutes or until the vegetables are tender. Add the chopped kohlrabi leaves during the last 5 minutes of the cooking time.
Add the cream cheese to the soup and blend the soup with an immersion blender (Note 2). Reheat the soup gently without bringing it to a boil again.
Season: Add salt, pepper, sugar, nutmeg, and one tablespoon of lemon juice. Taste again and adjust the taste with more lemon juice and more spices.
Serve: Sprinkle with the chopped parsley and maybe some red chili flakes and nigella seeds.