Preheat oven to 450 degrees.

Cut chicken into small pieces.

Spread chicken pieces on a large roasting pan.

Roast for 45 minutes or until crisply browned.

Scrape browned chicken and pan particles into a stockpot.

Cover with two inches of water.

Bring to a boil, then reduce heat and simmer for 45 minutes.

Stir occasionally to prevent sticking.

Set aside to cool.

Remove top layer of fat.

Return stock to a large pot and warm over medium heat.

Strain two cups of stock into a blender; reserve the rest.

On high speed, drizzle in olive oil until the sauce thickens and barely moves.

Season to taste with sherry vinegar, salt, and pepper.

Serve immediately.