expression, noun
butterflied and dried horse mackerel
A common dried fish product in Japan, often grilled and eaten as a side dish or in bento.
朝食にアジの開きを焼いた。
I grilled a butterflied dried horse mackerel for breakfast.
干物 is the general term for dried fish, while アジの開き specifically refers to a butterflied and dried horse mackerel.
Compound of アジ (horse mackerel) and 開き (opening, splitting), referring to the fish being split open and dried.