This is a my version of Zwiebelkuchen, a super popular dish. It's received the stamp of approval from my German friend.
German autumn meals are perhaps Zwiebelkuchen and Federweisser. This is a simplified recipe based off a popular German recipe site that I made with 4 friends.
Don't overcook the onions, they should be translucent, not golden brown.
Enjoy Japanese food around the world.