Pour 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, green onion, and red pepper flakes. Bring to a boil. Remove from heat, and cool 10-15 minutes. Place chicken pieces into a re-sealable plastic bag. When contents of saucepan have cooled, pour 1 cup of sauce into bag. Reserve the remaining sauce. Seal the bag, and refrigerate for at least 30 minutes. Heat the peanut and sesame oils in a large skillet over medium heat. Place chicken into the skillet, and brown on all sides. Dry on a plate lined with paper towels, and cover with aluminum foil to keep warm. Wipe out the skillet, and add the sauce. Bring to a boil over medium-high heat. Mix the cornstarch with 1 tablespoon water and stir into the sauce. Reduce heat to medium low. Add the chicken pieces and simmer for about 5 minutes, stirring occasionally. Serve alongside the stir fry and cooked rice, if desired.