If using frozen duck, completely defrost it in the refrigerator for 1-2 days. Once defrosted, take the duck out of the refrigerator 30 minutes before cooking to bring it more or less to room temperature. Take the giblets out of the duck, rinse it inside and outside, then pat dry using paper towels.
Preheat the oven to 350℉ (177℃).
Use a sharp knife to score the skin on the duck's breast in a diamond pattern, trying to cut only the skin without reaching the breast meat below. Poke the other fatty parts of the duck with the tip of the knife all over to ensure fat release, especially in very fatty parts. You don't need to poke the duck legs because the skin is thinner.
Season the duck generously with salt and pepper, including the cavity. Stuff the cavity with onion, garlic, lemon, orange, rosemary, sage, and thyme. The duck has flaps of skin on both ends - fold that skin inwards to hold in the ingredients and moisture during roasting.
Use 2-3 toothpicks to sew the skin around the cavity opening tightly together. Cross the legs and tie them together with cooking twine. Fold the wings under the duck.
Place the bird on the rack inside the roasting pan and cook at 350℉ (177℃) for 60 minutes, breast side up. After an hour, remove the bird and prick the skin all over again. Flip the duck breast-side down and roast for about 40 minutes.
While it's cooking, mix the glaze ingredients: honey, soy sauce, balsamic vinegar, lemon juice, orange juice, and sweet chili sauce in a medium pan. Then simmer over medium-high heat until it thickens, 7-10 minutes. Remove from heat and set aside.
After an hour and 40 minutes, remove the duck from the oven, and poke again. Flip the duck breast-side up again on a rack in a roasting pan. Brush the whole duck with the honey-balsamic mixture (especially the scored breast) and cook it breast-side up for another 40-50 minutes at 400℉ (205℃), brushing every 20 minutes with the mixture.
After the duck is cooked, remove it from the oven, and let it rest for 15 minutes. Then carefully remove and discard the lemon from the cavity.
Carve the duck and enjoy!