This is how the thigh is sold in the supermarket. If there are still pin feathers on it take them off. Wash off any bloody parts with water. I'll call the skin side the 'front' and the cut side the 'back'.
There are 3 parts to cut ★ [Bone]; [Skin] and [Cartilage]. The bone on the left side in the photo is a part I'd never seen in Japan, the base of the thigh (the chicken groin maybe?)
Cut off the skin at top center in the photo first. Next is the base of the thigh. Pull on the bone there as you cut along it to take it off.
The [skin] and [base of the thigh] have been removed. It may look like there's a lot of meat on that base bone, but it's actually mostly bone.
Cut through the upper bone along the bone, and open up the meat (until the bone is fully exposed).
Cut into the joint (the knee) with your knife. Hold the chicken with both hands, and break the joint.
When the joint is broken take the bottom bone out first. Pull on the bottom bone, and run your knife along it to cut off any sinews.
Next, before going to the upper bone, cut off the cartillage at the joint. I broke it in half and cut it, but use whatever method works best for you.
Remove the upper bone in the same way you removed the lower bone...and done!
Make it at home! Thinly cut meat recipe - Recipe ID: 1366903
There's a part at the base of the thigh called the "sot-l'y-laisse" in French, which means "only fools throw it away" (called the "oyster" in English).
Apparently this "sot-l'y-laisse" is very small and very precious, but I don't know where it is. If you know, please let me know!
Story Behind this Recipe
Boneless chicken thigh is not sold outside of Japan. So if they don't have it, there's nothing else to do but to do it yourself! In Germany, bone-in thigh costs way less than bread meat!
You may be a bit squeamish at first, but once you get used to it it really is easy! (I myself had never seen a the bone part at the base of the thigh before, so I was a bit freaked out at first... ^_^) If you leave a lot of meat on the bone the first time, don't worry, don't worry. ♪ (・∀・) You can just take it off afterwards!