Bring the vinegar, sugar, garlic and chilli to a boil in a heavy-bottomed saucepan. Cook over a high heat, stirring constantly, for approx. 2 min. Set the marinade aside.
Rub the duck legs with salt and place 2 of them, skin side down, in a large, heavy-bottomed saucepan (ovenproof). Turn up the heat and cook the legs, in their own fat, for about 6 min. over a medium heat – turn them over and continue cooking, still over a medium heat, for about 3 min. – remove the duck from the pan. Repeat the procedure with the last 2 duck legs. Return the first 2 duck legs to the saucepan and pour the chilli marinade over all 4 duck legs. Cover and finish cooking the duck in the middle of the oven for approx. 2 hours at 165°C (conventional oven).
Lightly whip the sour cream and the Castello Creamy Blue cheese for about 1 min. Add the orange zest, salt and pepper and season to taste.
Remove the peel and membranes from the oranges – follow the shape of the fruit. Cut along the membranes between the orange fillets to remove the orange flesh – save the juice. Combine the orange fillets, orange juice, red cabbage, cranberries and coriander leaves.
Warm the burger buns and slice them open. Pull the meat from the warm duck legs and combine with 4 tbsp of the chilli marinade from the saucepan. Spread blue dressing on the top and bottom of the burger buns and layer them with meat and red cabbage salad. Serve immediately.
Also a nice alternative for a luncheon during the holiday season and a good way to use leftovers. For a faster, but also very tasty version, you can use canned confit de canard.