Deviled Eggs - cooking recipe

Ingredients

12 eggs
2 tsp. vinegar
3/4 tsp. salt
1/8 tsp. pepper
1 tsp. mustard
2 Tbsp. butter
2 Tbsp. mayonnaise

Preparation

Boil eggs by placing in cold water in a saucepan.
Bring to a boil over medium heat.
Cover with a tight fitting lid; let stand 15 minutes.
Turn heat off.
Cool eggs by running cool water over them.
Peel eggs.
Slice in halves lengthwise.
Remove yolks from each egg.
Place the yolks in a bowl and mash.
Add the other ingredients.
Mix, making sure it is not lumpy.
Spoon mixture into the whites of the eggs.
Place in refrigerator to chill.