1/4 c. fresh basil leaves, firmly packed (may use dry basil)
1 c. mayonnaise
1/2 c. sour cream
1/2 c. chopped parsley
3 green onions with tops, chopped
3 tbsp. vinegar
1/8 tsp. dried tarragon
1 tsp. Worcestershire sauce
1/2 tsp. dry mustard
1/4 tsp. freshly ground pepper
1 clove garlic, minced
2 tbsp. chopped chives

Combine all ingredients in a blender. Blend until smooth.