"Satsuma-age" 薩摩揚げ is a deep fried fish cake which originated from the "Satsuma" 薩摩 region of Kyushu 九州, the southern island of Japan. This is often served in Izakaya. We occasionally have this as a "robatayaki" 炉端焼き item at Tako Grill. At home, I, like most people, ususally buy pre-made and frozen fish cakes. Just before serving, I thaw and grill (or toast them in a toaster oven). We eat these with grated ginger and soy sauce, which is pretty good. Another common use is to put them in "oden" おでん.
Since I bought a whole red snapper, I ended up with small bits of fish meat as well as meat I scraped off the bones after I filleted the fish. If this had been a salmon, I could have made a "salmon" cake in a very similar manner to "crab" cake. Although I never made this type of fish cakes before, I decided to make these fish meat scraps into a "Satsuma age". Mark's book p44 has a rather sophisticated version of this dish. I decided to use a simpler recipe which was in one of my cookbooks. In any case, I had only fish meat from red snapper but, typically, you should have a combination of two or more fish, usually cod plus some other white flesh fish to achieve good texture and taste according to these recipes. So, I knew mine would not be great before I even started making it.
First, I should have used a lower temperature oil and I should have used more fish meat or less egg white, liquid and grated nagaimo. Although this was quite edible (and my wife said it was even good) it is not "Satsuma age"--the consistency is totally wrong, much lighter and fluffier. I would call this "fried fish and nagaimo dumpling". I do not think I will make this one again. Store bought frozen ones are just fine.