Summertime Cerulean Blue Sauce
  Sky-blue sauce for summer

Take some of the wild blackberries that grow in hedgerows and some thoroughly pounded almonds, with a little ginger. And moisten these things with verjuice and strain through a sieve.
Toward the end of summer, when blackberries are at their best, this cerulean blue sauce will add zest to your September meat dinners. The pectin in the berries helps the sauce set to a lovely midnight-blue jelly that is a visual foil and a delicious accompaniment to white meats such as veal and chicken.

 1 quart (1 liter) blackberries
1/3 cup (50 g) unblanched almonds
2/3 cup verjuice, or a mixture of two parts cider vinegar to one part water
1/4-inch slice ginger, peeled

Puree the blackberries in a food processor or food mill, and strain the juice, pressing to extract as much liquid as possible. In a mortar or in a blender, grind the almonds and ginger, then mix with the blackberry juice. Contact with the air will turn the mixture a dark blue.
   Add the verjuice and strain once more. Season with salt to taste.

The Medieval Kitchen: Recipes from France and Italy
by Odile Redon, Françoise Sabban, & Silvano Serventi
Translated by Edward Schneider