Celery Soup(Sellerisuppe) - cooking recipe

Ingredients

2 celery roots
2 qt. water, boiling
1 tsp. salt
4 Tbsp. butter
4 Tbsp. flour
2 qt. stock or bouillon
1 egg yolk
1/2 c. small peas, cooked
1/4 tsp. white pepper
parsley, chopped
1/3 c. sherry

Preparation

Wash celery roots and pare them.
Cut each into 4 parts.
Cover with salted boiling water; cook until tender.
Drain.
Reserve 2 cups water.
Cut half of celery in small pieces and save for soup tureen.
Rub other half through sieve.
Melt butter in soup pot. Stir in flour.
Add liquid, little by little and let come to boil. Mix egg yolk with a little water and stir into soup.
Add the peas, pepper, salt and sherry.
Stir and pour over the celery into the soup tureen.
Add parsley.