Combine the chicken broth and garlic in a saucepan over medium-high heat. Bring to a boil, and cook until reduced by 1/2, at least 15 minutes. Stir in the cranberry raspberry concentrate, white wine, and 2/3 of the package of raspberries. Return to a boil, and boil until there is about 1/2 cup of sauce remaining, about 30 minutes. Strain the sauce, and return it to the pan. Mix together the cornstarch and cold water; stir into the sauce. Cook over medium heat until glossy and slightly thickened.
Place the flour and tarragon in a small paper sack. Shake to mix. Place chicken breasts in the bag, and coat completely.
Heat the olive oil in a skillet over medium heat. Add chicken, and cook until no longer pink, and the juices run clear. . Drain off excess oil, and pour the raspberry sauce into the pan. It will boil up, and then settle. Turn the chicken to coat evenly with the sauce. Sprinkle the remaining raspberries into the pan and cook until thawed.
