50 mlolive oil2small leeks, thinly sliced1½bulbs of baby fennel, thinly sliced using a mandolin (fronds reserved)3cloves of garlic, finely chopped1 (1.8kg)fresh organic chicken2bay leaves4pieces of lemon rind, removed with a peeler200 gmday-old crustless sourdough bread, coarsely torn150 gmfrozen peasTarragon sauce30 gmday-old crustless sourdough bread, coarsely torn50 mllemon juice25 mltarragon or white wine vinegar2hard-boiled egg yolks¾ cupeach of (loosely packed) tarragon and flat-leaf parsley leaves1clove of garlic, finely chopped150 mlolive oil
Heat oil in a large casserole over medium heat. Add leek, fennel and garlic and cook, stirring occasionally, until soft (10 minutes). Add chicken, bay leaves, lemon rind and 2½ litres cold water. Season with sea salt and freshly ground black pepper, weight down chicken with a plate and bring to a simmer over medium heat. Cover and cook gently until meat is falling from the bone (about 1 hour).
Remove chicken from casserole (let broth continue to simmer). When chicken is cool, coarsely shred meat (discard skin and bones) and return to soup, add bread, season, and continue simmering until soup thickens (about 5 minutes). Add peas, cook for another 1-2 minutes then stir in fennel fronds.
Meanwhile for tarragon sauce, soak bread in lemon juice and vinegar until soft (about 10 minutes). Transfer to food processor, then add egg yolks, herbs and garlic and process until smooth. Add olive oil in a steady stream and process to combine. Season to taste, then serve drizzled over bowls of hot broth.