Drain the mushrooms. Peel and quarter the onion and cut into strips. Peel and chop the garlic. Heat oil in a frying pan, fry gyros in it in 2-3 portions and take them out. Then fry onions and garlic in it. Add tomatoes and mash them with a spatula.
Pour in broth, add chili sauce, gyros, mushrooms, frozen green beans and oregano and bring to the boil. Cover and stew for 15-20 minutes. Crumble the feta. Season soup with salt and pepper and serve in deep bowls. Sprinkle with feta and olives. Garnish with fresh oregano
With 10 people: