In a large glass measuring cup, whisk together all the ingredients for the sauce, up to the ground ginger.
Heat the olive oil (or other healthy cooking fat of your choice) in a large, skillet set over high heat and sprinkle the pieces of chicken generously with salt. When the pan is hot enough, add half of the pieces of chicken, nice looking side down, and let the meat cook undisturbed for about 2 minutes, until it gets nice and golden at the bottom. Flip the pieces of chicken and continue cooking for another minute or two, until browned on the other side. Remove to a plate and repeat with the remaining pieces of chicken.
Once all the meat is cooked, return it to the skillet and pour the sauce in. Lower the heat and simmer, uncovered, for about 10 minutes, to finish cooking the chicken. Make a slurry by mixing the tapioca starch and water together, and then and then move the pieces chicken to the side, leaving a great big space in the middle of the pan to allow you to whisk the slurry in. Whisk constantly for about a minute, until the sauce is thickened, then delicately toss the chicken so it's completely covered with the sauce.
Serve immediately with a side of rice and garnished with a little bit of orange zest, if desired.