1 Place the stew meat in a stockpot with 1.5 liters (approximately 1 1/2 quarts) of water, season with salt and pepper and bring to a boil. Reduce to a simmer and cook over medium heat for 1 hour, adding more water if necessary to completely cover the meat.
2 Meanwhile, peel the potatoes, carrots, celery root and kohlrabi and cut them all into cubes. Rinse the leeks, shake dry, and cut the white and yellow parts into rings. Cut the green part into thin strips. Rinse and slice the zucchini. Rinse and core the cabbage. Separate the leaves and remove the thick stalks. Cut the cabbage into bite-size pieces.
3 Remove the meat from the broth, let cool briefly and cut into cubes. Add the vegetables to the beef broth and simmer over medium heat until tender, 20-25 minutes. Return the meat to the pot and cook until heated through. Season to taste and divide the soup among bowls. Serve garnished with the strips of leek greens.