Green Beans with Horseradish Sauce

Description
This recipe came from an estate sale. I obtained it when I purchased the family collection from the Day Estate in Fort Worth, Texas in 1982.
 * Contributed by Catsrecipes Y-Group

Ingredients

 * 2 pounds fresh green beans cooked
 * 1½ tablespoons butter
 * 1½ tablespoons flour
 * ¾ cup milk
 * 1 tablespoon grated white onion
 * ¼ teaspoon prepared mustard
 * ½ teaspoon prepared horseradish

Directions

 * 1) Sauté onion in butter then add flour and stir well.
 * 2) Add milk and cook until smooth and thick.
 * 3) Add horseradish and mustard.
 * 4) Pour sauce over warm beans and serve immediately.