1 c. mayonnaise
2 tsp. chopped anchovy (may be omitted)
1/2 tsp. dry mustard
1 tbsp. wine vinegar
1 tbsp. tarragon vinegar
2 tbsp. dry sherry
1/2 c. chopped parsley
1/4 tsp. garlic powder
4 tbsp. capers
1 tbsp. onion juice

Mix together and keep in refrigerator at least one day before using.