Pour 1 1/2 cups water, orange juice, lemon juice, rice vinegar, and soy sauce into a saucepan and set over medium-high heat. Stir in the orange zest, brown sugar, ginger, garlic, chopped onion, and red pepper flakes. Bring to a boil. Remove from heat, and cool 10 to 15 minutes.
Place the chicken pieces into a reseal able plastic bag. When contents of saucepan have cooled, pour 1 cup of sauce into bag. Reserve the remaining sauce. Seal the bag, and refrigerate at least 2 hours.
In another reseal able plastic bag, mix the flour, salt, and pepper. Add the marinated chicken pieces, seal the bag, and shake to coat.
Heat the olive oil in a large skillet over medium heat. Place chicken into the skillet, and brown on both sides. Drain on a plate lined with paper towels, and cover with aluminum foil.
Wipe out the skillet, and add the sauce. Bring to a boil over medium-high heat. Mix together the cornstarch and 2 tablespoons water; stir into the sauce. Reduce heat to medium low; add the chicken pieces, and simmer, about 5 minutes, stirring occasionally.
Serve with steamed jasmine rice.
* I usually skip the marinating part and just make the sauce. I dip the chicken pieces in a batter of 4 egg whites, Whip egg whites in a medium bowl until foamy. Stir in 2/3cup of mochiko until it has a pasty consistency. Dip the pieces in the batter and deep fry. This batter gives it a light fluffy texture, the way you get them in the restaurants. You can find Mochiko in the Asian aisle of most grocery stores. Flour will not produce the same kind of texture; it really is worth finding the mochiko if you plan on making it this way.