500g (1lb) boneless, skinless chicken thighs OR 500g (1lb) shredded chicken from a ready-cooked rotisserie chicken
a little chopped parsley to garnish
Heat up the olive oil in a large, heavy based saucepan. Add the onion, celery, carrots and garlic and cook gently until the vegetables have softened - probably about 10 minutes.
Add the tomato purée and stir to coat the vegetables. Allow this to cook for a minute or so.
Now add the chicken stock and the lentils and bring to a boil.
Reduce the heat to a simmer and add the chicken thighs to the pan. Leave to cook for about 40 minutes, occasionally checking to make sure that nothing is sticking and that the liquid is not bubbling too ferociously.
When the lentils are ready, remove the chicken thighs with a slotted spoon and put them on a plate to cool before shredding the meat with a pair of forks.
Stir the shredded chicken back into the soup, check for seasoning and garnish with a little chopped parsley.
I reserve 1/2 litre (2 cups) of the chicken stock and add it towards the end of cooking if I think the consistency needs it. It will depend on how thick you prefer your soup.