Step 1: 1) Fill a pan with water (enough to easily cover the lentils) and bring to the boil. Add the lentils and simmer for 5-10 minutes (untill the water has discoloured slightly).
Step 3: 2) While the lentils are simmering prepare and grate the onion and garlic.
Step 5: 3) Strain the lentils and boil more water in the pan. There should be enough to cover the lentils by about 3cm. Enough for the lentils to reduce into a fairly thick soup.
Step 7: 4) Add the lentils again with the onion, garlic, tomato purée, salt, pepper, splash of olive oil and a shake of oregano.
Step 9: 5) Simmer the soup and stir at intervals ensuring the mixture does not stick. Do not be afraid of leaving the mixture untill it has reduced to a fairly thick texture; it may take up to 30 minutes.
Step 11: 6) While the mixture is simmering prepare the feta cheese by removing from the packet and shaking oregano and olive oil over the top. Cut it into squares (approx 1cm cubes).
Step 13: 7) When the soup has reached the desired consistency, leave to stand for 2 minutes then add half of the cheese and stir. Searve the dish with more oregano to taste and more feta cheese on top.