Heat a little oil in a soup pot.
If you make it with meat, add it now, season with salt and ground black pepper. Stir constantly for about 3 minutes or until the meat has been seared on all sides.
Add the whole peeled onion, the carrots, the parsley roots (or parsnips), the cubed kohlrabies, the green peas and the Brussel sprouts. Add 1,5 liters of water, salt to taste and simmer until the vegetables are tender.
In the meantime, you have to prepare the semolina dumplings.
In a bowl mix 2 whole eggs with 1/2 cup of semolina. Do not whisk the eggs, just stir gently. Do not add any salt to the mixture. Put it in the refrigerator for about 5 minutes, the semolina will absorb some moisture, the batter will get thicker.
In a larger pot heat 1 liter of water, add 1 level tablespoon of salt, bring it to a boil.
Form the dumplings and gently drop them in the water.
How to shape the dumplings: form small, ellipse-shaped dumplings using two tablespoons. Here is a short video, it helps you to make them. Drop the dumplings in the boiling water, cover with a lid and simmer for about 10 minutes. They will double in size. Remove, place them onto a plate, and serve in the hot soup.