Warm duck legs confit by following the instructions on the package.
Meanwhile, prepare the sauce. In a small saucepan, sauté the onions in butter 2 minutes. Add remaining ingredients except blueberries, salt and pepper to taste.
Bring to a boil, then reduce heat to medium. Simmer until liquid is reduced by half. Remove from heat and add a handful of fresh blueberries to the sauce.
Generously drizzle each plate with balsamic blueberry sauce, and then top with a confit. Garnish with fresh blueberries and serve immediately. Serve with mashed potatoes, carrots with honey and sweet spices and a green salad.
