In a medium bowl, combine beer, soy sauce, sugar, garlic, ginger, oyster sauce, star anise, green onion and chicken broth.
Place duck in an oven-proof pan, roaster or casserole dish. Spoon mixture over duck and rub some inside duck. Refrigerate overnight, turning the duck in the marinade 4 times.
Heat oven to 375° F.
Place duck, breast side up, on a wire rack that will fit inside pan used for marinade. Return duck, on wire rack, to pan; place in oven. Roast 45 minutes, turn over and roast 45 minutes again. (For looks, if you wish, flip duck after 30 minutes and let roast final 15 minutes breast side up.) Remove from oven and place duck on a platter. Carve duck into slices.
Pour sauce and pan juices into a saucepan, scrape off anything that sticks to the pan. (If necessary, add enough chicken stock to make about 2 cups liquid.) Dissolve cornstarch in 3 tablespoons cold water; add to sauce pan and bring to a boil, whisking if necessary to prevent lumps. Cook 1 minute, until somewhat thickened. Spoon over duck slices and serve immediately.Makes 6 to 8 Source: