One thing I'm really enjoying here in Japan is cooking simple things at home with my mother. To me, quintessential Japanese home cooking is a dish like this. Sardines, which happen to be quite inexpensive (and sustainable too), are slowly cooked until they are well flavored, meltingly soft, and glossy with a typically Japanese sweet-salty sauce. (The 'kanroni' (甘露煮) in the name refers to the method of simmering something in this sweet-salty sauce.) It uses just a few basic ingredients, so please give it a try if you can get a hold of very fresh sardines or similar oily fish. (The fish do have to be very fresh for this to be really good and not-fishy.)
I had a bit of a job working out this recipe, which comes from my mother, since she really doesn't measure anything when she makes this! After some trial and error, I think these ingredient amounts work well.