1 c. mayonnaise
1 c. sour cream
2 tbsp. chopped onion
1 lg. or 2 sm. cloves garlic, minced
1 tsp. salt
1/2 tsp. black pepper
1/2 c. chopped parsley
1 tbsp. Dijon mustard (key ingredient)

Blend and refrigerate for 2-3 hours.