Sour Sauce - cooking recipe

Ingredients

1 small onion, chopped
1/4 c. vinegar
1 c. water
2 Tbsp. melted butter
2 egg yolks
1 Tbsp. flour
1/2 tsp. salt

Preparation

Combine in saucepan the onions, vinegar and water.
Cook 10 minutes.
Blend together butter, egg yolks, flour and salt.
Pour hot liquid over butter mixture.
Blend thoroughly.
Simmer 1 minute to make mixture smooth.