Wash the chicken and place it in a large pot.  Add the water and bring to boil.  Lower the heat and skim off any froth that has appeared.  Add  the vegetables, the thyme, and the peppercorns, and let simmer till the chicken is  "drop off the bone" done.

Remove the chicken and the vegetables from the stock.  Add the rice and the salt.  Let cook for approximately 15 minutes, till the rice is tender.

Pulverize the vegetables with a little stock in the food processor, till smooth.  Add to the stock.

In a bowl (or a food processor) whisk the egg whites.  Then beat in the egg yolks, and lastly beat in the lemon juice.  While beating, temper the sauce with  a little of the hot stock.  Once the temperature of the egg-lemon sauce has reached that of the stock's, pour it into the soup, stir, and serve.