To make the marinade: Put the garlic, rice wine, honey, chile sauce, light soy sauce, cinnamon, ginger, and allspice into a bowl or resealable plastic food bag, and set aside.
To make the duck: Add the duck legs to the marinade, cover with plastic wrap, and leave in the refrigerator to marinate for as long as possible, preferably overnight.
To make the salad: Put the radish, cucumber, chile, if using, cilantro, rice vinegar, sugar, salt, and rice wine, in a bowl and toss to combine. Cover the bowl with plastic wrap, and set aside in the refrigerator for 1 hour.
To finish the duck: Preheat an oven to 350 degrees F.
Place the duck legs, skin side up, in a roasting pan, and roast for 10 minutes. Then, raise the temperature of the oven to 425 degrees F for 5 minutes to cook the meat to well done. Remove the duck from the oven, and set aside for 2 minutes, to cool slightly.
Cut the duck meat into bite-sized slices, and dust the slices in the flour to coat well.
Heat a wok or heavy-bottomed pan over a high heat, and fill it to a quarter of its depth with enough groundnut oil.
Heat the oil to 350 degrees F, or until a cube of bread dropped in it turns golden brown in 15 seconds. Place the duck pieces in a spider scoop or wire strainer, and lower them into the oil and fry until crispy, and golden brown. Remove the duck from the pan, and drain on an absorbent kitchen towel to remove the excess oil.
To serve, spoon some pickled radish salad onto a serving plate and lay some of the crispy duck slices over the top. Sprinkle a pinch of salt, and some dried chile flakes over the duck pieces and serve immediately.
Ensure your wok is stable before deep-frying.