Chicken and Vegetables with Tarragon Sauce

Peel carrots and turnips and cut into chunks or slices.

Rinse, trim and thinly slice leeks crosswise.

Rinse, trim and slice celery.

Bring chicken broth to a boil in a large saucepan. Rinse chicken pieces and add to broth. Reduce heat and simmer about 30 minutes, skimming foam occasionally. 

Add vegetables, cover and simmer 30 minutes more. With a ladle, transfer 0.5 liter (approximately 2 cups) broth to a bowl and let cool slightly. In a saucepan, whisk together creme fraiche and egg yolks. Gradually whisk in broth. Stirring constantly, cook over very low heat until mixture thickens (do not boil!). Add tarragon and season with salt and pepper.