Seems like everybody, like me, immediately notice the strange tale of frying. Growing enough beans to produce oil is not easy and extracting them is a labour intensive process, Japan not familiar with frying is sort of understandable. Their shortage of iron prevents experiment with cooking utensils. In Austronesian cultures, similar to Japan, doesn't have a reliable source of iron, most of iron products were imported from China or Siam, hence their cooking methods were limited. Life without iron is very interesting. Rice were cooked in clay pot, which is a delicacy now. They also added other ingredients onto the rice and cook them together. Baking were done similarly, though because there's no wheat, any form of bread involving gluten is nonexistent. Instead their baked products is a gelatinous ball of rice flour, which can be stuffed with sweat or salty ingredients. Meat on the other hand is very fun since they also can be stew, grill and bake just like iron civilisations through clay pot and even a form of frying through banana leaves. A popular way to cook is wrapping raw food in banana leaves to grill, boil or steam, since banana leaves have high oil content and highly accessible. It's remarkable how far those cultures went without much iron in their daily life. The only metal products in their household probably only consist of the hoe, scythe and knife. Even then, those cultures had wooden hoe, bone and stone scythe and knife before iron superseded them.