I have long been a Karaage fan but my attempts to recreate it at home never lived up to the restaurant version. I recently acquired a bag of tapioca flour and everything changed; I was able to get that indescribably crunchy and delicious crust, without deep frying. Internet research indicates that potato flour or even cornstarch will work in a pinch.
2 boneless, skinless chicken thighs, cut into bite-sized pieces
2 tsps oyster sauce
1 tsp soy sauce
1 tsp sake, Vermouth or dry white wine
1/2 tsp grated fresh ginger root
2 Tbsps tapioca flour
1 Tbsp vegetable oil
Half a lemon
Salt to taste
Mix the oyster sauce, soy sauce, sake and ginger together in a bowl. Add the chicken pieces and toss well to combine. Cover and refrigerate well for at least two hours, preferably overnight.
When ready to use, toss the chicken pieces again in whatever remains of the marinade. Salt lightly and toss again. Measure the tapioca flour into a bowl or large Ziplock bag.
Remove the chicken from the marinade and toss the damp pieces with the tapioca flour until lightly coated on all sides. A sort of dryish batter will cover each piece of chicken when you are done, thicker in some places than others depending on where your chicken was the dampest. This is normal and just fine.
Heat the oil in a skillet over medium until shimmering. Add the chicken pieces and cook for three minutes on one side and two and a half on the other. You do not want to crowd the pan or the chicken will steam rather than crisp so you may want to do this in two rounds of cooking.
Remove to a paper towel lined plate to absorb excess oil before sprinkling each piece with finishing salt and a generous squeeze of lemon juice.
I made these twice, the first time as part of a traditional Japanese dinner with steamed rice, pickled umeboshi plums and broccoli cooked in dashi broth, the second time on top of a traditional Caesar salad. Both were delicious, my only caveat is that the crust does not stay crispy forever and the chicken should be eaten at once -- not exactly a hardship...