Combine first 3 ingredients in a large bowl, stirring well and mashing fruit with the back of a wooden spoon to release juices. Cover tightly, and refrigerate 24 hours. Stir in vinegar. Cover tightly, and refrigerate 3 hours. Stir well, and strain through a fine-mesh sieve, pressing gently on solids. Discard solids.

Combine ingredients in a pitcher. To prepare each cocktail: pour the desired amount of cocktail mixture in to an ice-filled shaker and shake vigorously 30 seconds; strain into a glass. Garnish creatively with a lemon twist and fresh basil leaves or a rhubarb spear, as desired.