I tried this recipe that I found at recipelink last night. It was very good although not quite like Panda Express. I served it over fried rice (I bought that at the Chinese place, had to cut down on time) If you try this, make sure that the chicken gets crispy.

Panda Express Orange Chicken

2 lbs boneless chicken pieces, skinned
1 egg
1 1/2 tsp salt
white pepper
1/2 c plus 1 Tbsp cornstarch
1/4 c flour
1 tbsp minced ginger root
1 tsp minced garlic
dash crushed hot red chiles
1/4 c chopped green onions
1 tbsp rice wine
Orange Chicken Sauce
1/4 c water
1/2 to 1 tsp sesame oil

Cut chicken pieces into 2-inch squares and place in large bowl. Stir in egg,
salt, pepper, and 1 tbsp oil and mix well. Stir cornstarch and flour
together. Add chicken pieces, stirring to coat.
Heat oil for deep-frying in wok or deep-fryer to 375 degrees. Add chicken
pieces, small batch at time, and fry 3 to 4 minutes or until golden and crisp.
(Do not overcook or chicken will be tough.) Remove chicken from oil with
slotted spoon and drain on paper towels. Set aside.
Clean wok and heat 15 seconds over high heat. Add 1 tbsp oil. Add ginger
and garlic and stir-fry until fragrant. Add and stir-fry crushed chiles and
green onions. Add rice wine and stir 3 seconds. Add Orange Sauce and bring
to boil. Add cooked chicken, stirring until well mixed. Stir water into
remaining 1 tbsp cornstarch until smooth.
Add to chickn and heat until sauce is thickened. Stir in 1 tbsp oil and
sesame oil. Serve at once. Makes 6 servings.

Orange Chicken Sauce

1 1/2 tbsp soy sauce
1 1/2 tbsp water
5 tbsp sugar
5 tbsp white vinegar

Mix soy sauce, water, sugar and vinegar together.