Debbie's Mushroom Soup

500g mushrooms, peeled and sliced
1 leek, sliced
1 potato, diced into small cubes
3 sticks celery, sliced
1 onion, finely chopped
2 cloves garlic, finely chopped
2 parve chicken stock cubes [Massel]
1 tablespoon olive oil
20g butter [optional]

Saute onions and garlic in some olive oil and a knob of butter [butter optional but it does make a difference].
Add chopped leek and celery.
Saute for a few minutes.
Then add mushrooms, potato, stock cubes, salt and pepper and enough water to just cover.
Bring to boil and simmer for about 40 minutes.
Blend and serve.