To prepare this Greek beef soup recipe, first cut the beef into 5cm (2 inches) pieces.
Fill a large pot with 2 1/2 liters of water and bring to a boil.
Once water is boiling add the beef, cover and boil for 45 minutes,
During this cooking time, cut all the vegetables.
Chop the onions, cut the potatoes into large pieces, the carrots into rounds, the leek into rounds, the celery into slices, the zucchini into half moons and chop the celery leaves. Set aside.
Once meat is done boiling, remove meat from the pot and set aside. Strain the broth and set aside.
In the large pot add the olive oil. Place on medium heat and saute all the vegetables except for the zucchini for about 5 minutes. The zucchini will be added to the soup in the last 15 minutes of cooking.
After the 5 minutes add in the beef and saute with the vegetables another 5 minutes. Add in the broth (should be about 1.5 to 2 liters, otherwise add a bit of water). Season with salt and pepper.
Cover the pot, bring to a boil and then lower the heat to simmer, medium low heat. Cook for 45 minutes. Remember to put in the zucchini before the time is up!
Once it is done take the pot off the heat.