Leek and Potato Soup

Ingredients

• 2 tablespoons olive oil (or 1 tablespoon oil and 15 g / 1/2 oz butter)
• 1 medium onion (peeled and roughly diced )
• 1 stick celery (washed, stringy bits removed and diced )
• 2 cloves garlic ( crushed or chopped )
• 2 large leeks (washed, trimmed and diced (see tips below) )
• 1 large potato (or 2 medium - peeled and diced )
• 1&1/2 pints stock ( or water and 1/2 stock cube or milk or half and half)
• seasoning (to taste )
• 2 tablespoons chives or parsley ( chopped (optional) )