|Onion||1 Medium, finely chopped|
|Potatoes||1 1⁄2 Pound, peeled and diced|
|Broth||1 Quart (Hot)|
|Hot water||1 Quart|
|Milk||1 Cup (16 tbs)|
Saute onion in 2 tablespoons of the butter until soft.
Add flour and stir until bubbly.
Add hot broth and water.
Stir to blend.
Add potatoes and salt.
Bring to a rapid boil, cover, and boil for 30 minutes.
Strain, pressing vegetables through sieve.
Return soup to heat and bring back to a boil.
When ready to serve, remove from heat and gradually stir in egg yolks beaten with the milk and a little of the hot soup.
Stir in remaining butter and serve hot.