In a pot, whisk together the vinegar, orange juice, brown sugar and 1/2 cup of the stock and bring to a boil. Place the remaining stock and cornstarch into a small bowl, stir to combine and then whisk into the pot. Bring back to a boil and cook until the sauce lightly thickens. Add the cherries and mint and season with salt and pepper. Reserve the sauce on low heat while you grill the chicken.
Preheat an indoor or outdoor grill to medium-high. Brush the chicken with the oil, and season with cumin, salt and pepper. Lightly oil the grill. Grill the chicken 4 to 5 minutes per side, or until cooked through. Place the chicken on plates, top with the sauce and serve.