The sauce for this better-than-take-out orange chicken can be made ahead for minimal prep in the evening!
For the Sauce:
Combine all ingredients except the slurry in a sauce pan and bring to a boil. Add the slurry and continue to boil until the mixture thickens a bit. Set aside.
In a medium bowl, whisk the rice flour, AP flour salt and pepper together.
In a small bowl beat the egg with about four ounces of the club soda and then whisk that into the flour mixture adding more club soda as you need to make a batter slightly thicker than thin. Heat the oil in a large frying pan, dip the chicken pieces into the batter, shaking off any excess and then fry them on both sides until lightly browned. Transfer the browned chicken pieces to a rimmed baking sheet and bake in a 425F oven for about ten minutes.
Pour the reserved sauce into a wok or large frying pan, bring up to the boil and then gently stir in the sesame oil, broccoli, water chestnuts and browned chicken pieces. Serve the chicken mixture over the rice and lettuce and garnish with the green onion.