Lentil and garlic soup with minted yoghurt

1.Heat oil in large saucepan. Add garlic and thyme. Cook, stirring, until garlic softens. Stir in lentils, then add stock and water; bring to the boil. Reduce heat. Simmer, covered, about 35 minutes, or until lentils soften.

2.Meanwhile, make the minted yoghurt: in a small bowl, combine all ingredients.

3.Using a food processor or blendor, process the soup, in batches, until pureed. Return to pan. Add watercress to soup; cook, stirring, until wilted. Serve soup with minted yoghurt.