1Skin and cut the duck breast into 1/2-inch cubes. In a bowl, combine the duck, sherry, soy sauce and salt, then refrigerate for 30 minutes.
2Mince the garlic and ginger. Cut the onion and bell peppers into 1-inch chunks. Drain the pineapple and reserve one tablespoon of the juice for the sauce. In a small bowl, combine the sauce ingredients.
In another small bowl, combine the thickener ingredients
In a shallow baking dish, beat the egg with a fork until well blended.
3On waxed paper, add 1/2 cup of flour.
On another piece of waxed paper, combine the remaining 1/2 cup flour with the baking powder.
4Dredge the duck into the flour, then into the beaten egg, and finally into the flour with the baking powder.
5Heat wok over high heat, then add enough oil until it's 2 inches deep. Heat the oil. Add one piece of duck. If the meat sizzles, the oil is hot enough. Add the remaining duck, stir constantly, and cook for 4 minutes, or until lightly browned.
Remove the duck and drain.
Place duck in warm oven.
6Remove the oil from the wok and reserve for other cooking. Clean the wok. Heat the wok over medium-high heat and add 2 teaspoons of reserved oil. Add the garlic and ginger and cook for 30 seconds. Pour in the sauce ingredients along with the onion, bell peppers, and pineapple. Stir and cook about 3 minutes or until the vegetables are tender but slightly crisp. Add the thickener mixture, stir, and cook until thick. Return the duck to the sauce and stir until coated, about 30 seconds. Serve at once over rice.