Pour 1/2 cup chicken stock, vinegar, orange juice and honey into a saucepan. Bring to a boil over high heat then reduce heat to medium. Dissolve cornflour in 1/4 cup of chicken stock and stir into the simmering sauce. Cook and stir until the sauce thickens and turns clear, 1 to 2 minutes. Stir in the blueberries and chives and keep warm over low heat.
Preheat barbecue to medium high-heat.
Brush salmon with oil and season to taste with salt and pepper. Cook until the fish flakes easily with a fork, about 3 to 4 minutes per side. Serve with blueberry sauce.