As the favorite (konomi) ingredients were put in, they were called konomiyaki, but they thought the name was not appropriate and added "o" to the name and the name okonomiyaki seems to have appeared.
好きな具材を入れていく事で好み焼き、しかしこの名称では良くないのではとなり、頭におを付けてお好み焼きになったらしい。