Chicken Blackberry Vinegar

For Blackberry Vinegar: Soak the blackberries in the vinegar for 3 hours, then pass the mixture through a food mill. Discard the seeds.

For Demi-Glace: Brown the beef bones and put them in a large stockpot. Cover with water and boil. Keep the bones covered with water for 8 to 10 hours. Strain, reserving the liquid.

Put the beef bones in the pot with the chicken bones, vegetables and seasonings. Cover with water and cook for 4 to 5 hours.

Strain, reserving the liquid. Combine both the beef liquid and the chicken liquid together. Bring to a boil and then add the tomato puree. Cook for 10 minutes, then strain.

Increase heat and reduce until the liquid will coat a spoon. Skim the surface of the mixture throughout the reduction.

Any leftover demi-glace can be frozen in an ice cube tray and used a cube at a time later.

For Chicken: Saute the chicken and then remove it from the pan. Drain off the fat and deglaze the pan with blackberry vinegar. Add the chicken and demi-glace. Bring to a boil. Finish with butter.

Remove chicken to serving plates and cover with sauce.