The recipe in the Mark's book (p54) is interesting, since the chicken is first macerated in salt and sake and then dressed in soy sauce just before it was dredged in flour and deep fried. I will try that in the near future but, here, I used my more traditional recipe. I bone, clean and cut up chicken thigh into bite size pieces across the grain of the meat. I then marinate the chicken in a Ziploc bag containing sake, mirin, and soy sauce (1:1:2 ratio) and 1/2 tsp of grated ginger (optional) for at least 30 minutes to several hours or even overnight. (For shorter marinating time, increase soy sauce in the marinade.) I lift the chicken pieces from the marinade, pat dry with paper towels, dredge in potato flour or "katakuri-ko" 片栗粉 and deep fry. I actually use a "shallow" frying method as you see below. I use the amount of oil (peanut oil) to the depth of 1/2 inch so it comes to half the thickness of the chicken pieces. The oil temperature should be about 350F but I use the bamboo-chop-stick-dipped-in-oil method of judging the oil temperature. The shallow frying will all moisture to escape more easily from the chicken pieces (since half is exposed to air) and produce a crispier outer layer besides using less oil. (I learned this technique from a chicken "kara-age" recipe in a cook book by Kentaro Kobayashi, which lists many small dishes that go with drinks). I fry for 3-5 minutes and toward the end, crank up the heat a bit to make the surface crispy (cut to test for doneness). I drain the chicken of excess oil on a metal grate before serving. I serve this dish on a folded tempura "shikishi" paper 天ぷら敷き紙, but it is obviously not necessary if you do not have one.
You only need lemon wedges, or not even that, since the chicken pieces are already seasoned. We try not to make and eat too much deep fried food but this one is really good especially since we have not had this for some times.
Last time we were in Kyoto, we had chicken Kara-age at "Tori-hachi" 鳥八 (A specialized chicken dish drinking place but not "yakitori"-ya) near Kyoto station. They have two large vats of oil on induction cookers with electronic thermal sensors to maintain the high and low temperatures and they use a double frying method to produce an excellent "kara-age".