Peel the celery and 2 carrots, clean and wash the leek. Coarsely chop the celery, carrots and half of the leek. Peel and quarter onion. Clean and wash the mushrooms. Wash and slice the tomato
Heat the oil in a pot. Sauté the onion, celery and chopped carrots in it. Add the chopped leek, mushrooms and tomato and fry briefly. Season with salt and pepper. Add 1 l water and bring to the boil. Cover and simmer for about 45 minutes
Peel and wash the kohlrabi and 3 carrots. Cut kohlrabi into small cubes, carrots into thin sticks. Cut the rest of the leek into rings. Sieve broth and bring to the boil. Cover the vegetables and cook for 7-10 minutes
4 .cut or dice the toast into lozenges. Fry in hot fat until golden brown. Season the bouillon with salt, pepper and possibly soy sauce. Serve with the croutons