Remove as much fat from chicken as possible (some people also like to pull off as much skin as they can; this reduces the fat content of the broth).

Put the chicken in a deep soup pot. Add water to barely cover it, and sprinkle in the salt. Bring the water rapidly to a boil over high heat.

Skim off the foam on the surface of the water, then add the turnips, onions, garlic, celery, and parsley. Reduce the heat to low and cover the pot. Simmer the chicken for 1 1/2 hours, or until tender.

Remove the chicken from the pot and cut into serving pieces. Keep warm on a serving platter.

Strain the broth, then let cool to room temperature. Use a paper towel to skim as much fat from the surface of the broth as possible.

Reheat broth over high heat and then boil it, uncovered, for 15 minutes to reduce somewhat.

Grate the lemon rind and add the grated peel to the broth. Squeeze the lemon juice and mix well with the cornstarch.

Remove broth from the heat and add potato starch mixture, stirring until smooth.

Pour the thickened cooking liquid into the top part of a double boiler, and place over hot water.

Keep double boiler on a low heat and, stirring constantly, add the beaten egg yolks to the broth. Stir constantly until the sauce thickens.

Serve the chicken with a little of the sauce poured over; have more sauce on the side.