As it happens,"Circassian" also denotes a similarly highly valued strain of English walnut, richly textured in swirls and curves in shades of brown and black.
This beautiful, spirited, and richly textured dish of chicken and walnuts is a Turkish classic.
Place the chicken in a large pot. Chop the celery, carrot, a large onion, and half the garlic, and add to the pot with the parsley, thyme, bay leaves, and peppercorns. Add enough water to cover the chicken and bring to a boil. Reduce the heat and simmer for about ninety minutes, skimming occasionally, until the chicken is done. Remove the meat, discard the skin, and return the bones to the pot. Continue simmering for at least two hours more, adding salt to taste, until the stock is quite rich. Strain, chill, and remove the fat.
Reserve a few walnut halves for garnish and grind the rest in a food processor, Soak the bread, with crusts removed, in water. Squeeze out the water and add the bread to the processor with the remaining garlic and onion, chopped. Grind until smooth and transfer to a bowl. Mix in three tablespoons paprika, the cayenne, and enough stock (about 2 cups) to make a sauce. Add salt to taste. Cut the cooked meat into pieces and mix with half the sauce.
At serving time, sauté the reserved walnuts in a tablespoon of oil until lightly toasted. Heat the remaining three tablespoons of oil with a tablespoon of paprika. Spread the chicken on a platter and cover with the remaining sauce, thinned out with a little more stock. Garnish with the walnuts, and spoon the oil and paprika mixture on top. Serve at room temperature.