Place all ingredients for the bbq sauce in a medium sized pot. Over medium heat, simmer until cherries are tender and sugar is dissolved, about 7 minutes.
Pour pots contents into a blender and blend on high until mixture is smooth. Refrigerate until room temp, stirring 1-2 times. Makes about 2 ½ cups.
While bbq sauce is cooling, make the chicken marinade. In a small bowl mix the olive oil, mustard, minced garlic, salt, pepper and brown sugar. Place the chicken in a bowl with a tight fitting lid. Pour marinade over chicken, cover with lid, shake to coat the chicken.
Heat grill to medium-high heat and lightly oil grate. Cook chicken on the prepared grill 10-15 minutes per side, or until no longer pink and juices run clear. Coat the chicken with cherry-balsamic bbq sauce while grilling.
While Chicken is on the grill, make the couscous. Heat oil in a medium frying pan. Add dry couscous and sprigs of thyme, stirring until toasted and turning slightly golden brown. In a separate pot (with tight fitting lid) bring chicken stock and water to a boil. Add toasted couscous to boiling stock, cover with a tight fitting lid, remove from heat and let rest for 10 minutes. After 10 minutes the couscous will be tender. If any liquid remains, turn heat back on and simmer, stirring frequently until all the water is absorbed.
To serve, place ¼ of the herbed couscous onto each plate, top with bbq chicken and desired amount of bbq sauce and sprinkle with flat leaf parsley.